mirror of https://github.com/python/cpython
1712 lines
65 KiB
ReStructuredText
1712 lines
65 KiB
ReStructuredText
:mod:`inspect` --- Inspect live objects
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=======================================
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.. testsetup:: *
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import inspect
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from inspect import *
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.. module:: inspect
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:synopsis: Extract information and source code from live objects.
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.. moduleauthor:: Ka-Ping Yee <ping@lfw.org>
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.. sectionauthor:: Ka-Ping Yee <ping@lfw.org>
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**Source code:** :source:`Lib/inspect.py`
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--------------
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The :mod:`inspect` module provides several useful functions to help get
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information about live objects such as modules, classes, methods, functions,
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tracebacks, frame objects, and code objects. For example, it can help you
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examine the contents of a class, retrieve the source code of a method, extract
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and format the argument list for a function, or get all the information you need
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to display a detailed traceback.
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There are four main kinds of services provided by this module: type checking,
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getting source code, inspecting classes and functions, and examining the
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interpreter stack.
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.. _inspect-types:
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Types and members
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-----------------
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The :func:`getmembers` function retrieves the members of an object such as a
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class or module. The functions whose names begin with "is" are mainly
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provided as convenient choices for the second argument to :func:`getmembers`.
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They also help you determine when you can expect to find the following special
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attributes (see :ref:`import-mod-attrs` for module attributes):
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.. this function name is too big to fit in the ascii-art table below
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.. |coroutine-origin-link| replace:: :func:`sys.set_coroutine_origin_tracking_depth`
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+-----------+-------------------+---------------------------+
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| Type | Attribute | Description |
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+===========+===================+===========================+
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| class | __doc__ | documentation string |
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+-----------+-------------------+---------------------------+
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| | __name__ | name with which this |
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| | | class was defined |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | __module__ | name of module in which |
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| | | this class was defined |
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+-----------+-------------------+---------------------------+
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| method | __doc__ | documentation string |
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+-----------+-------------------+---------------------------+
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| | __name__ | name with which this |
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| | | method was defined |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | __func__ | function object |
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| | | containing implementation |
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| | | of method |
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+-----------+-------------------+---------------------------+
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| | __self__ | instance to which this |
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| | | method is bound, or |
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| | | ``None`` |
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+-----------+-------------------+---------------------------+
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| | __module__ | name of module in which |
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| | | this method was defined |
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+-----------+-------------------+---------------------------+
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| function | __doc__ | documentation string |
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+-----------+-------------------+---------------------------+
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| | __name__ | name with which this |
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| | | function was defined |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | __code__ | code object containing |
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| | | compiled function |
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| | | :term:`bytecode` |
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+-----------+-------------------+---------------------------+
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| | __defaults__ | tuple of any default |
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| | | values for positional or |
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| | | keyword parameters |
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+-----------+-------------------+---------------------------+
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| | __kwdefaults__ | mapping of any default |
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| | | values for keyword-only |
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| | | parameters |
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+-----------+-------------------+---------------------------+
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| | __globals__ | global namespace in which |
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| | | this function was defined |
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+-----------+-------------------+---------------------------+
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| | __builtins__ | builtins namespace |
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+-----------+-------------------+---------------------------+
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| | __annotations__ | mapping of parameters |
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| | | names to annotations; |
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| | | ``"return"`` key is |
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| | | reserved for return |
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| | | annotations. |
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+-----------+-------------------+---------------------------+
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| | __module__ | name of module in which |
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| | | this function was defined |
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+-----------+-------------------+---------------------------+
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| traceback | tb_frame | frame object at this |
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| | | level |
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+-----------+-------------------+---------------------------+
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| | tb_lasti | index of last attempted |
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| | | instruction in bytecode |
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+-----------+-------------------+---------------------------+
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| | tb_lineno | current line number in |
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| | | Python source code |
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+-----------+-------------------+---------------------------+
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| | tb_next | next inner traceback |
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| | | object (called by this |
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| | | level) |
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+-----------+-------------------+---------------------------+
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| frame | f_back | next outer frame object |
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| | | (this frame's caller) |
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+-----------+-------------------+---------------------------+
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| | f_builtins | builtins namespace seen |
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| | | by this frame |
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+-----------+-------------------+---------------------------+
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| | f_code | code object being |
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| | | executed in this frame |
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+-----------+-------------------+---------------------------+
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| | f_globals | global namespace seen by |
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| | | this frame |
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+-----------+-------------------+---------------------------+
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| | f_lasti | index of last attempted |
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| | | instruction in bytecode |
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+-----------+-------------------+---------------------------+
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| | f_lineno | current line number in |
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| | | Python source code |
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+-----------+-------------------+---------------------------+
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| | f_locals | local namespace seen by |
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| | | this frame |
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+-----------+-------------------+---------------------------+
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| | f_trace | tracing function for this |
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| | | frame, or ``None`` |
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+-----------+-------------------+---------------------------+
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| code | co_argcount | number of arguments (not |
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| | | including keyword only |
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| | | arguments, \* or \*\* |
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| | | args) |
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+-----------+-------------------+---------------------------+
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| | co_code | string of raw compiled |
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| | | bytecode |
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+-----------+-------------------+---------------------------+
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| | co_cellvars | tuple of names of cell |
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| | | variables (referenced by |
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| | | containing scopes) |
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+-----------+-------------------+---------------------------+
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| | co_consts | tuple of constants used |
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| | | in the bytecode |
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+-----------+-------------------+---------------------------+
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| | co_filename | name of file in which |
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| | | this code object was |
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| | | created |
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+-----------+-------------------+---------------------------+
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| | co_firstlineno | number of first line in |
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| | | Python source code |
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+-----------+-------------------+---------------------------+
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| | co_flags | bitmap of ``CO_*`` flags, |
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| | | read more :ref:`here |
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| | | <inspect-module-co-flags>`|
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+-----------+-------------------+---------------------------+
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| | co_lnotab | encoded mapping of line |
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| | | numbers to bytecode |
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| | | indices |
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+-----------+-------------------+---------------------------+
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| | co_freevars | tuple of names of free |
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| | | variables (referenced via |
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| | | a function's closure) |
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+-----------+-------------------+---------------------------+
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| | co_posonlyargcount| number of positional only |
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| | | arguments |
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+-----------+-------------------+---------------------------+
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| | co_kwonlyargcount | number of keyword only |
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| | | arguments (not including |
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| | | \*\* arg) |
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+-----------+-------------------+---------------------------+
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| | co_name | name with which this code |
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| | | object was defined |
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+-----------+-------------------+---------------------------+
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| | co_qualname | fully qualified name with |
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| | | which this code object |
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| | | was defined |
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+-----------+-------------------+---------------------------+
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| | co_names | tuple of names other |
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| | | than arguments and |
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| | | function locals |
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+-----------+-------------------+---------------------------+
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| | co_nlocals | number of local variables |
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+-----------+-------------------+---------------------------+
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| | co_stacksize | virtual machine stack |
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| | | space required |
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+-----------+-------------------+---------------------------+
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| | co_varnames | tuple of names of |
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| | | arguments and local |
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| | | variables |
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+-----------+-------------------+---------------------------+
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| generator | __name__ | name |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | gi_frame | frame |
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+-----------+-------------------+---------------------------+
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| | gi_running | is the generator running? |
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+-----------+-------------------+---------------------------+
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| | gi_code | code |
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+-----------+-------------------+---------------------------+
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| | gi_yieldfrom | object being iterated by |
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| | | ``yield from``, or |
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| | | ``None`` |
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+-----------+-------------------+---------------------------+
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| coroutine | __name__ | name |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | cr_await | object being awaited on, |
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| | | or ``None`` |
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+-----------+-------------------+---------------------------+
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| | cr_frame | frame |
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+-----------+-------------------+---------------------------+
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| | cr_running | is the coroutine running? |
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+-----------+-------------------+---------------------------+
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| | cr_code | code |
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+-----------+-------------------+---------------------------+
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| | cr_origin | where coroutine was |
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| | | created, or ``None``. See |
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| | | |coroutine-origin-link| |
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+-----------+-------------------+---------------------------+
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| builtin | __doc__ | documentation string |
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+-----------+-------------------+---------------------------+
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| | __name__ | original name of this |
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| | | function or method |
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+-----------+-------------------+---------------------------+
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| | __qualname__ | qualified name |
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+-----------+-------------------+---------------------------+
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| | __self__ | instance to which a |
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| | | method is bound, or |
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| | | ``None`` |
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+-----------+-------------------+---------------------------+
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.. versionchanged:: 3.5
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Add ``__qualname__`` and ``gi_yieldfrom`` attributes to generators.
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The ``__name__`` attribute of generators is now set from the function
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name, instead of the code name, and it can now be modified.
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.. versionchanged:: 3.7
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Add ``cr_origin`` attribute to coroutines.
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.. versionchanged:: 3.10
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Add ``__builtins__`` attribute to functions.
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.. function:: getmembers(object[, predicate])
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Return all the members of an object in a list of ``(name, value)``
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pairs sorted by name. If the optional *predicate* argument—which will be
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called with the ``value`` object of each member—is supplied, only members
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for which the predicate returns a true value are included.
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.. note::
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:func:`getmembers` will only return class attributes defined in the
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metaclass when the argument is a class and those attributes have been
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listed in the metaclass' custom :meth:`~object.__dir__`.
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.. function:: getmembers_static(object[, predicate])
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Return all the members of an object in a list of ``(name, value)``
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pairs sorted by name without triggering dynamic lookup via the descriptor
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protocol, __getattr__ or __getattribute__. Optionally, only return members
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that satisfy a given predicate.
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.. note::
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:func:`getmembers_static` may not be able to retrieve all members
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that getmembers can fetch (like dynamically created attributes)
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and may find members that getmembers can't (like descriptors
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that raise AttributeError). It can also return descriptor objects
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instead of instance members in some cases.
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.. versionadded:: 3.11
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.. function:: getmodulename(path)
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Return the name of the module named by the file *path*, without including the
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names of enclosing packages. The file extension is checked against all of
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the entries in :func:`importlib.machinery.all_suffixes`. If it matches,
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the final path component is returned with the extension removed.
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Otherwise, ``None`` is returned.
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Note that this function *only* returns a meaningful name for actual
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Python modules - paths that potentially refer to Python packages will
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still return ``None``.
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.. versionchanged:: 3.3
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The function is based directly on :mod:`importlib`.
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.. function:: ismodule(object)
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Return ``True`` if the object is a module.
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.. function:: isclass(object)
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Return ``True`` if the object is a class, whether built-in or created in Python
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code.
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.. function:: ismethod(object)
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Return ``True`` if the object is a bound method written in Python.
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.. function:: isfunction(object)
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Return ``True`` if the object is a Python function, which includes functions
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created by a :term:`lambda` expression.
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.. function:: isgeneratorfunction(object)
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Return ``True`` if the object is a Python generator function.
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.. versionchanged:: 3.8
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Functions wrapped in :func:`functools.partial` now return ``True`` if the
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wrapped function is a Python generator function.
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.. function:: isgenerator(object)
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Return ``True`` if the object is a generator.
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.. function:: iscoroutinefunction(object)
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Return ``True`` if the object is a :term:`coroutine function` (a function
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defined with an :keyword:`async def` syntax), a :func:`functools.partial`
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wrapping a :term:`coroutine function`, or a sync function marked with
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:func:`markcoroutinefunction`.
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.. versionadded:: 3.5
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.. versionchanged:: 3.8
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Functions wrapped in :func:`functools.partial` now return ``True`` if the
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wrapped function is a :term:`coroutine function`.
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.. versionchanged:: 3.12
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Sync functions marked with :func:`markcoroutinefunction` now return
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``True``.
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.. function:: markcoroutinefunction(func)
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Decorator to mark a callable as a :term:`coroutine function` if it would not
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otherwise be detected by :func:`iscoroutinefunction`.
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This may be of use for sync functions that return a :term:`coroutine`, if
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the function is passed to an API that requires :func:`iscoroutinefunction`.
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When possible, using an :keyword:`async def` function is preferred. Also
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acceptable is calling the function and testing the return with
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:func:`iscoroutine`.
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.. versionadded:: 3.12
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.. function:: iscoroutine(object)
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Return ``True`` if the object is a :term:`coroutine` created by an
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:keyword:`async def` function.
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.. versionadded:: 3.5
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.. function:: isawaitable(object)
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Return ``True`` if the object can be used in :keyword:`await` expression.
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Can also be used to distinguish generator-based coroutines from regular
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generators:
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.. testcode::
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import types
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def gen():
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yield
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@types.coroutine
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def gen_coro():
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yield
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assert not isawaitable(gen())
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assert isawaitable(gen_coro())
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.. versionadded:: 3.5
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.. function:: isasyncgenfunction(object)
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Return ``True`` if the object is an :term:`asynchronous generator` function,
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for example:
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.. doctest::
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>>> async def agen():
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... yield 1
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...
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>>> inspect.isasyncgenfunction(agen)
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True
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.. versionadded:: 3.6
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.. versionchanged:: 3.8
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Functions wrapped in :func:`functools.partial` now return ``True`` if the
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wrapped function is a :term:`asynchronous generator` function.
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.. function:: isasyncgen(object)
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Return ``True`` if the object is an :term:`asynchronous generator iterator`
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created by an :term:`asynchronous generator` function.
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.. versionadded:: 3.6
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.. function:: istraceback(object)
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Return ``True`` if the object is a traceback.
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.. function:: isframe(object)
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Return ``True`` if the object is a frame.
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.. function:: iscode(object)
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Return ``True`` if the object is a code.
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.. function:: isbuiltin(object)
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Return ``True`` if the object is a built-in function or a bound built-in method.
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.. function:: ismethodwrapper(object)
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Return ``True`` if the type of object is a :class:`~types.MethodWrapperType`.
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These are instances of :class:`~types.MethodWrapperType`, such as :meth:`~object.__str__`,
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:meth:`~object.__eq__` and :meth:`~object.__repr__`.
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.. versionadded:: 3.11
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.. function:: isroutine(object)
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Return ``True`` if the object is a user-defined or built-in function or method.
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.. function:: isabstract(object)
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Return ``True`` if the object is an abstract base class.
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.. function:: ismethoddescriptor(object)
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Return ``True`` if the object is a method descriptor, but not if
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:func:`ismethod`, :func:`isclass`, :func:`isfunction` or :func:`isbuiltin`
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are true.
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This, for example, is true of ``int.__add__``. An object passing this test
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has a :meth:`~object.__get__` method but not a :meth:`~object.__set__`
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method, but beyond that the set of attributes varies. A
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:attr:`~definition.__name__` attribute is usually
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sensible, and :attr:`!__doc__` often is.
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Methods implemented via descriptors that also pass one of the other tests
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return ``False`` from the :func:`ismethoddescriptor` test, simply because the
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other tests promise more -- you can, e.g., count on having the
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:attr:`~method.__func__` attribute (etc) when an object passes
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:func:`ismethod`.
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.. function:: isdatadescriptor(object)
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Return ``True`` if the object is a data descriptor.
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Data descriptors have a :attr:`~object.__set__` or a :attr:`~object.__delete__` method.
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Examples are properties (defined in Python), getsets, and members. The
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latter two are defined in C and there are more specific tests available for
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those types, which is robust across Python implementations. Typically, data
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descriptors will also have :attr:`~definition.__name__` and :attr:`!__doc__` attributes
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(properties, getsets, and members have both of these attributes), but this is
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not guaranteed.
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.. function:: isgetsetdescriptor(object)
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Return ``True`` if the object is a getset descriptor.
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.. impl-detail::
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getsets are attributes defined in extension modules via
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:c:type:`PyGetSetDef` structures. For Python implementations without such
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types, this method will always return ``False``.
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.. function:: ismemberdescriptor(object)
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Return ``True`` if the object is a member descriptor.
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.. impl-detail::
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Member descriptors are attributes defined in extension modules via
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:c:type:`PyMemberDef` structures. For Python implementations without such
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types, this method will always return ``False``.
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.. _inspect-source:
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Retrieving source code
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----------------------
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.. function:: getdoc(object)
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Get the documentation string for an object, cleaned up with :func:`cleandoc`.
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If the documentation string for an object is not provided and the object is
|
|
a class, a method, a property or a descriptor, retrieve the documentation
|
|
string from the inheritance hierarchy.
|
|
Return ``None`` if the documentation string is invalid or missing.
|
|
|
|
.. versionchanged:: 3.5
|
|
Documentation strings are now inherited if not overridden.
|
|
|
|
|
|
.. function:: getcomments(object)
|
|
|
|
Return in a single string any lines of comments immediately preceding the
|
|
object's source code (for a class, function, or method), or at the top of the
|
|
Python source file (if the object is a module). If the object's source code
|
|
is unavailable, return ``None``. This could happen if the object has been
|
|
defined in C or the interactive shell.
|
|
|
|
|
|
.. function:: getfile(object)
|
|
|
|
Return the name of the (text or binary) file in which an object was defined.
|
|
This will fail with a :exc:`TypeError` if the object is a built-in module,
|
|
class, or function.
|
|
|
|
|
|
.. function:: getmodule(object)
|
|
|
|
Try to guess which module an object was defined in. Return ``None``
|
|
if the module cannot be determined.
|
|
|
|
|
|
.. function:: getsourcefile(object)
|
|
|
|
Return the name of the Python source file in which an object was defined
|
|
or ``None`` if no way can be identified to get the source. This
|
|
will fail with a :exc:`TypeError` if the object is a built-in module, class, or
|
|
function.
|
|
|
|
|
|
.. function:: getsourcelines(object)
|
|
|
|
Return a list of source lines and starting line number for an object. The
|
|
argument may be a module, class, method, function, traceback, frame, or code
|
|
object. The source code is returned as a list of the lines corresponding to the
|
|
object and the line number indicates where in the original source file the first
|
|
line of code was found. An :exc:`OSError` is raised if the source code cannot
|
|
be retrieved.
|
|
A :exc:`TypeError` is raised if the object is a built-in module, class, or
|
|
function.
|
|
|
|
.. versionchanged:: 3.3
|
|
:exc:`OSError` is raised instead of :exc:`IOError`, now an alias of the
|
|
former.
|
|
|
|
|
|
.. function:: getsource(object)
|
|
|
|
Return the text of the source code for an object. The argument may be a module,
|
|
class, method, function, traceback, frame, or code object. The source code is
|
|
returned as a single string. An :exc:`OSError` is raised if the source code
|
|
cannot be retrieved.
|
|
A :exc:`TypeError` is raised if the object is a built-in module, class, or
|
|
function.
|
|
|
|
.. versionchanged:: 3.3
|
|
:exc:`OSError` is raised instead of :exc:`IOError`, now an alias of the
|
|
former.
|
|
|
|
|
|
.. function:: cleandoc(doc)
|
|
|
|
Clean up indentation from docstrings that are indented to line up with blocks
|
|
of code.
|
|
|
|
All leading whitespace is removed from the first line. Any leading whitespace
|
|
that can be uniformly removed from the second line onwards is removed. Empty
|
|
lines at the beginning and end are subsequently removed. Also, all tabs are
|
|
expanded to spaces.
|
|
|
|
|
|
.. _inspect-signature-object:
|
|
|
|
Introspecting callables with the Signature object
|
|
-------------------------------------------------
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
The :class:`Signature` object represents the call signature of a callable object
|
|
and its return annotation. To retrieve a :class:`!Signature` object,
|
|
use the :func:`!signature`
|
|
function.
|
|
|
|
.. function:: signature(callable, *, follow_wrapped=True, globals=None, locals=None, eval_str=False)
|
|
|
|
Return a :class:`Signature` object for the given *callable*:
|
|
|
|
.. doctest::
|
|
|
|
>>> from inspect import signature
|
|
>>> def foo(a, *, b:int, **kwargs):
|
|
... pass
|
|
|
|
>>> sig = signature(foo)
|
|
|
|
>>> str(sig)
|
|
'(a, *, b: int, **kwargs)'
|
|
|
|
>>> str(sig.parameters['b'])
|
|
'b: int'
|
|
|
|
>>> sig.parameters['b'].annotation
|
|
<class 'int'>
|
|
|
|
Accepts a wide range of Python callables, from plain functions and classes to
|
|
:func:`functools.partial` objects.
|
|
|
|
If the passed object has a ``__signature__`` attribute, this function
|
|
returns it without further computations.
|
|
|
|
For objects defined in modules using stringized annotations
|
|
(``from __future__ import annotations``), :func:`signature` will
|
|
attempt to automatically un-stringize the annotations using
|
|
:func:`get_annotations`. The
|
|
*globals*, *locals*, and *eval_str* parameters are passed
|
|
into :func:`get_annotations` when resolving the
|
|
annotations; see the documentation for :func:`get_annotations`
|
|
for instructions on how to use these parameters.
|
|
|
|
Raises :exc:`ValueError` if no signature can be provided, and
|
|
:exc:`TypeError` if that type of object is not supported. Also,
|
|
if the annotations are stringized, and *eval_str* is not false,
|
|
the ``eval()`` call(s) to un-stringize the annotations in :func:`get_annotations`
|
|
could potentially raise any kind of exception.
|
|
|
|
A slash(/) in the signature of a function denotes that the parameters prior
|
|
to it are positional-only. For more info, see
|
|
:ref:`the FAQ entry on positional-only parameters <faq-positional-only-arguments>`.
|
|
|
|
.. versionchanged:: 3.5
|
|
The *follow_wrapped* parameter was added.
|
|
Pass ``False`` to get a signature of
|
|
*callable* specifically (``callable.__wrapped__`` will not be used to
|
|
unwrap decorated callables.)
|
|
|
|
.. versionchanged:: 3.10
|
|
The *globals*, *locals*, and *eval_str* parameters were added.
|
|
|
|
.. note::
|
|
|
|
Some callables may not be introspectable in certain implementations of
|
|
Python. For example, in CPython, some built-in functions defined in
|
|
C provide no metadata about their arguments.
|
|
|
|
|
|
.. class:: Signature(parameters=None, *, return_annotation=Signature.empty)
|
|
|
|
A :class:`!Signature` object represents the call signature of a function
|
|
and its return
|
|
annotation. For each parameter accepted by the function it stores a
|
|
:class:`Parameter` object in its :attr:`parameters` collection.
|
|
|
|
The optional *parameters* argument is a sequence of :class:`Parameter`
|
|
objects, which is validated to check that there are no parameters with
|
|
duplicate names, and that the parameters are in the right order, i.e.
|
|
positional-only first, then positional-or-keyword, and that parameters with
|
|
defaults follow parameters without defaults.
|
|
|
|
The optional *return_annotation* argument can be an arbitrary Python object.
|
|
It represents the "return" annotation of the callable.
|
|
|
|
:class:`!Signature` objects are *immutable*. Use :meth:`Signature.replace` or
|
|
:func:`copy.replace` to make a modified copy.
|
|
|
|
.. versionchanged:: 3.5
|
|
:class:`!Signature` objects are now picklable and :term:`hashable`.
|
|
|
|
.. attribute:: Signature.empty
|
|
|
|
A special class-level marker to specify absence of a return annotation.
|
|
|
|
.. attribute:: Signature.parameters
|
|
|
|
An ordered mapping of parameters' names to the corresponding
|
|
:class:`Parameter` objects. Parameters appear in strict definition
|
|
order, including keyword-only parameters.
|
|
|
|
.. versionchanged:: 3.7
|
|
Python only explicitly guaranteed that it preserved the declaration
|
|
order of keyword-only parameters as of version 3.7, although in practice
|
|
this order had always been preserved in Python 3.
|
|
|
|
.. attribute:: Signature.return_annotation
|
|
|
|
The "return" annotation for the callable. If the callable has no "return"
|
|
annotation, this attribute is set to :attr:`Signature.empty`.
|
|
|
|
.. method:: Signature.bind(*args, **kwargs)
|
|
|
|
Create a mapping from positional and keyword arguments to parameters.
|
|
Returns :class:`BoundArguments` if ``*args`` and ``**kwargs`` match the
|
|
signature, or raises a :exc:`TypeError`.
|
|
|
|
.. method:: Signature.bind_partial(*args, **kwargs)
|
|
|
|
Works the same way as :meth:`Signature.bind`, but allows the omission of
|
|
some required arguments (mimics :func:`functools.partial` behavior.)
|
|
Returns :class:`BoundArguments`, or raises a :exc:`TypeError` if the
|
|
passed arguments do not match the signature.
|
|
|
|
.. method:: Signature.replace(*[, parameters][, return_annotation])
|
|
|
|
Create a new :class:`Signature` instance based on the instance
|
|
:meth:`replace` was invoked on.
|
|
It is possible to pass different *parameters* and/or
|
|
*return_annotation* to override the corresponding properties of the base
|
|
signature. To remove ``return_annotation`` from the copied
|
|
:class:`!Signature`, pass in
|
|
:attr:`Signature.empty`.
|
|
|
|
.. doctest::
|
|
|
|
>>> def test(a, b):
|
|
... pass
|
|
...
|
|
>>> sig = signature(test)
|
|
>>> new_sig = sig.replace(return_annotation="new return anno")
|
|
>>> str(new_sig)
|
|
"(a, b) -> 'new return anno'"
|
|
|
|
:class:`Signature` objects are also supported by the generic function
|
|
:func:`copy.replace`.
|
|
|
|
.. method:: format(*, max_width=None)
|
|
|
|
Create a string representation of the :class:`Signature` object.
|
|
|
|
If *max_width* is passed, the method will attempt to fit
|
|
the signature into lines of at most *max_width* characters.
|
|
If the signature is longer than *max_width*,
|
|
all parameters will be on separate lines.
|
|
|
|
.. versionadded:: 3.13
|
|
|
|
.. classmethod:: Signature.from_callable(obj, *, follow_wrapped=True, globals=None, locals=None, eval_str=False)
|
|
|
|
Return a :class:`Signature` (or its subclass) object for a given callable
|
|
*obj*.
|
|
|
|
This method simplifies subclassing of :class:`Signature`:
|
|
|
|
.. testcode::
|
|
|
|
class MySignature(Signature):
|
|
pass
|
|
sig = MySignature.from_callable(sum)
|
|
assert isinstance(sig, MySignature)
|
|
|
|
Its behavior is otherwise identical to that of :func:`signature`.
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
.. versionchanged:: 3.10
|
|
The *globals*, *locals*, and *eval_str* parameters were added.
|
|
|
|
|
|
.. class:: Parameter(name, kind, *, default=Parameter.empty, annotation=Parameter.empty)
|
|
|
|
:class:`!Parameter` objects are *immutable*.
|
|
Instead of modifying a :class:`!Parameter` object,
|
|
you can use :meth:`Parameter.replace` or :func:`copy.replace` to create a modified copy.
|
|
|
|
.. versionchanged:: 3.5
|
|
Parameter objects are now picklable and :term:`hashable`.
|
|
|
|
.. attribute:: Parameter.empty
|
|
|
|
A special class-level marker to specify absence of default values and
|
|
annotations.
|
|
|
|
.. attribute:: Parameter.name
|
|
|
|
The name of the parameter as a string. The name must be a valid
|
|
Python identifier.
|
|
|
|
.. impl-detail::
|
|
|
|
CPython generates implicit parameter names of the form ``.0`` on the
|
|
code objects used to implement comprehensions and generator
|
|
expressions.
|
|
|
|
.. versionchanged:: 3.6
|
|
These parameter names are now exposed by this module as names like
|
|
``implicit0``.
|
|
|
|
.. attribute:: Parameter.default
|
|
|
|
The default value for the parameter. If the parameter has no default
|
|
value, this attribute is set to :attr:`Parameter.empty`.
|
|
|
|
.. attribute:: Parameter.annotation
|
|
|
|
The annotation for the parameter. If the parameter has no annotation,
|
|
this attribute is set to :attr:`Parameter.empty`.
|
|
|
|
.. attribute:: Parameter.kind
|
|
|
|
Describes how argument values are bound to the parameter. The possible
|
|
values are accessible via :class:`Parameter` (like ``Parameter.KEYWORD_ONLY``),
|
|
and support comparison and ordering, in the following order:
|
|
|
|
.. tabularcolumns:: |l|L|
|
|
|
|
+------------------------+----------------------------------------------+
|
|
| Name | Meaning |
|
|
+========================+==============================================+
|
|
| *POSITIONAL_ONLY* | Value must be supplied as a positional |
|
|
| | argument. Positional only parameters are |
|
|
| | those which appear before a ``/`` entry (if |
|
|
| | present) in a Python function definition. |
|
|
+------------------------+----------------------------------------------+
|
|
| *POSITIONAL_OR_KEYWORD*| Value may be supplied as either a keyword or |
|
|
| | positional argument (this is the standard |
|
|
| | binding behaviour for functions implemented |
|
|
| | in Python.) |
|
|
+------------------------+----------------------------------------------+
|
|
| *VAR_POSITIONAL* | A tuple of positional arguments that aren't |
|
|
| | bound to any other parameter. This |
|
|
| | corresponds to a ``*args`` parameter in a |
|
|
| | Python function definition. |
|
|
+------------------------+----------------------------------------------+
|
|
| *KEYWORD_ONLY* | Value must be supplied as a keyword argument.|
|
|
| | Keyword only parameters are those which |
|
|
| | appear after a ``*`` or ``*args`` entry in a |
|
|
| | Python function definition. |
|
|
+------------------------+----------------------------------------------+
|
|
| *VAR_KEYWORD* | A dict of keyword arguments that aren't bound|
|
|
| | to any other parameter. This corresponds to a|
|
|
| | ``**kwargs`` parameter in a Python function |
|
|
| | definition. |
|
|
+------------------------+----------------------------------------------+
|
|
|
|
Example: print all keyword-only arguments without default values:
|
|
|
|
.. doctest::
|
|
|
|
>>> def foo(a, b, *, c, d=10):
|
|
... pass
|
|
|
|
>>> sig = signature(foo)
|
|
>>> for param in sig.parameters.values():
|
|
... if (param.kind == param.KEYWORD_ONLY and
|
|
... param.default is param.empty):
|
|
... print('Parameter:', param)
|
|
Parameter: c
|
|
|
|
.. attribute:: Parameter.kind.description
|
|
|
|
Describes a enum value of :attr:`Parameter.kind`.
|
|
|
|
.. versionadded:: 3.8
|
|
|
|
Example: print all descriptions of arguments:
|
|
|
|
.. doctest::
|
|
|
|
>>> def foo(a, b, *, c, d=10):
|
|
... pass
|
|
|
|
>>> sig = signature(foo)
|
|
>>> for param in sig.parameters.values():
|
|
... print(param.kind.description)
|
|
positional or keyword
|
|
positional or keyword
|
|
keyword-only
|
|
keyword-only
|
|
|
|
.. method:: Parameter.replace(*[, name][, kind][, default][, annotation])
|
|
|
|
Create a new :class:`Parameter` instance based on the instance replaced was invoked
|
|
on. To override a :class:`!Parameter` attribute, pass the corresponding
|
|
argument. To remove a default value or/and an annotation from a
|
|
:class:`!Parameter`, pass :attr:`Parameter.empty`.
|
|
|
|
.. doctest::
|
|
|
|
>>> from inspect import Parameter
|
|
>>> param = Parameter('foo', Parameter.KEYWORD_ONLY, default=42)
|
|
>>> str(param)
|
|
'foo=42'
|
|
|
|
>>> str(param.replace()) # Will create a shallow copy of 'param'
|
|
'foo=42'
|
|
|
|
>>> str(param.replace(default=Parameter.empty, annotation='spam'))
|
|
"foo: 'spam'"
|
|
|
|
:class:`Parameter` objects are also supported by the generic function
|
|
:func:`copy.replace`.
|
|
|
|
.. versionchanged:: 3.4
|
|
In Python 3.3 :class:`Parameter` objects were allowed to have ``name`` set
|
|
to ``None`` if their ``kind`` was set to ``POSITIONAL_ONLY``.
|
|
This is no longer permitted.
|
|
|
|
.. class:: BoundArguments
|
|
|
|
Result of a :meth:`Signature.bind` or :meth:`Signature.bind_partial` call.
|
|
Holds the mapping of arguments to the function's parameters.
|
|
|
|
.. attribute:: BoundArguments.arguments
|
|
|
|
A mutable mapping of parameters' names to arguments' values.
|
|
Contains only explicitly bound arguments. Changes in :attr:`arguments`
|
|
will reflect in :attr:`args` and :attr:`kwargs`.
|
|
|
|
Should be used in conjunction with :attr:`Signature.parameters` for any
|
|
argument processing purposes.
|
|
|
|
.. note::
|
|
|
|
Arguments for which :meth:`Signature.bind` or
|
|
:meth:`Signature.bind_partial` relied on a default value are skipped.
|
|
However, if needed, use :meth:`BoundArguments.apply_defaults` to add
|
|
them.
|
|
|
|
.. versionchanged:: 3.9
|
|
:attr:`arguments` is now of type :class:`dict`. Formerly, it was of
|
|
type :class:`collections.OrderedDict`.
|
|
|
|
.. attribute:: BoundArguments.args
|
|
|
|
A tuple of positional arguments values. Dynamically computed from the
|
|
:attr:`arguments` attribute.
|
|
|
|
.. attribute:: BoundArguments.kwargs
|
|
|
|
A dict of keyword arguments values. Dynamically computed from the
|
|
:attr:`arguments` attribute.
|
|
|
|
.. attribute:: BoundArguments.signature
|
|
|
|
A reference to the parent :class:`Signature` object.
|
|
|
|
.. method:: BoundArguments.apply_defaults()
|
|
|
|
Set default values for missing arguments.
|
|
|
|
For variable-positional arguments (``*args``) the default is an
|
|
empty tuple.
|
|
|
|
For variable-keyword arguments (``**kwargs``) the default is an
|
|
empty dict.
|
|
|
|
.. doctest::
|
|
|
|
>>> def foo(a, b='ham', *args): pass
|
|
>>> ba = inspect.signature(foo).bind('spam')
|
|
>>> ba.apply_defaults()
|
|
>>> ba.arguments
|
|
{'a': 'spam', 'b': 'ham', 'args': ()}
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
The :attr:`args` and :attr:`kwargs` properties can be used to invoke
|
|
functions:
|
|
|
|
.. testcode::
|
|
|
|
def test(a, *, b):
|
|
...
|
|
|
|
sig = signature(test)
|
|
ba = sig.bind(10, b=20)
|
|
test(*ba.args, **ba.kwargs)
|
|
|
|
|
|
.. seealso::
|
|
|
|
:pep:`362` - Function Signature Object.
|
|
The detailed specification, implementation details and examples.
|
|
|
|
|
|
.. _inspect-classes-functions:
|
|
|
|
Classes and functions
|
|
---------------------
|
|
|
|
.. function:: getclasstree(classes, unique=False)
|
|
|
|
Arrange the given list of classes into a hierarchy of nested lists. Where a
|
|
nested list appears, it contains classes derived from the class whose entry
|
|
immediately precedes the list. Each entry is a 2-tuple containing a class and a
|
|
tuple of its base classes. If the *unique* argument is true, exactly one entry
|
|
appears in the returned structure for each class in the given list. Otherwise,
|
|
classes using multiple inheritance and their descendants will appear multiple
|
|
times.
|
|
|
|
|
|
.. function:: getfullargspec(func)
|
|
|
|
Get the names and default values of a Python function's parameters. A
|
|
:term:`named tuple` is returned:
|
|
|
|
``FullArgSpec(args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults,
|
|
annotations)``
|
|
|
|
*args* is a list of the positional parameter names.
|
|
*varargs* is the name of the ``*`` parameter or ``None`` if arbitrary
|
|
positional arguments are not accepted.
|
|
*varkw* is the name of the ``**`` parameter or ``None`` if arbitrary
|
|
keyword arguments are not accepted.
|
|
*defaults* is an *n*-tuple of default argument values corresponding to the
|
|
last *n* positional parameters, or ``None`` if there are no such defaults
|
|
defined.
|
|
*kwonlyargs* is a list of keyword-only parameter names in declaration order.
|
|
*kwonlydefaults* is a dictionary mapping parameter names from *kwonlyargs*
|
|
to the default values used if no argument is supplied.
|
|
*annotations* is a dictionary mapping parameter names to annotations.
|
|
The special key ``"return"`` is used to report the function return value
|
|
annotation (if any).
|
|
|
|
Note that :func:`signature` and
|
|
:ref:`Signature Object <inspect-signature-object>` provide the recommended
|
|
API for callable introspection, and support additional behaviours (like
|
|
positional-only arguments) that are sometimes encountered in extension module
|
|
APIs. This function is retained primarily for use in code that needs to
|
|
maintain compatibility with the Python 2 ``inspect`` module API.
|
|
|
|
.. versionchanged:: 3.4
|
|
This function is now based on :func:`signature`, but still ignores
|
|
``__wrapped__`` attributes and includes the already bound first
|
|
parameter in the signature output for bound methods.
|
|
|
|
.. versionchanged:: 3.6
|
|
This method was previously documented as deprecated in favour of
|
|
:func:`signature` in Python 3.5, but that decision has been reversed
|
|
in order to restore a clearly supported standard interface for
|
|
single-source Python 2/3 code migrating away from the legacy
|
|
:func:`getargspec` API.
|
|
|
|
.. versionchanged:: 3.7
|
|
Python only explicitly guaranteed that it preserved the declaration
|
|
order of keyword-only parameters as of version 3.7, although in practice
|
|
this order had always been preserved in Python 3.
|
|
|
|
|
|
.. function:: getargvalues(frame)
|
|
|
|
Get information about arguments passed into a particular frame. A
|
|
:term:`named tuple` ``ArgInfo(args, varargs, keywords, locals)`` is
|
|
returned. *args* is a list of the argument names. *varargs* and *keywords*
|
|
are the names of the ``*`` and ``**`` arguments or ``None``. *locals* is the
|
|
locals dictionary of the given frame.
|
|
|
|
.. note::
|
|
This function was inadvertently marked as deprecated in Python 3.5.
|
|
|
|
|
|
.. function:: formatargvalues(args[, varargs, varkw, locals, formatarg, formatvarargs, formatvarkw, formatvalue])
|
|
|
|
Format a pretty argument spec from the four values returned by
|
|
:func:`getargvalues`. The format\* arguments are the corresponding optional
|
|
formatting functions that are called to turn names and values into strings.
|
|
|
|
.. note::
|
|
This function was inadvertently marked as deprecated in Python 3.5.
|
|
|
|
|
|
.. function:: getmro(cls)
|
|
|
|
Return a tuple of class cls's base classes, including cls, in method resolution
|
|
order. No class appears more than once in this tuple. Note that the method
|
|
resolution order depends on cls's type. Unless a very peculiar user-defined
|
|
metatype is in use, cls will be the first element of the tuple.
|
|
|
|
|
|
.. function:: getcallargs(func, /, *args, **kwds)
|
|
|
|
Bind the *args* and *kwds* to the argument names of the Python function or
|
|
method *func*, as if it was called with them. For bound methods, bind also the
|
|
first argument (typically named ``self``) to the associated instance. A dict
|
|
is returned, mapping the argument names (including the names of the ``*`` and
|
|
``**`` arguments, if any) to their values from *args* and *kwds*. In case of
|
|
invoking *func* incorrectly, i.e. whenever ``func(*args, **kwds)`` would raise
|
|
an exception because of incompatible signature, an exception of the same type
|
|
and the same or similar message is raised. For example:
|
|
|
|
.. doctest::
|
|
|
|
>>> from inspect import getcallargs
|
|
>>> def f(a, b=1, *pos, **named):
|
|
... pass
|
|
...
|
|
>>> getcallargs(f, 1, 2, 3) == {'a': 1, 'named': {}, 'b': 2, 'pos': (3,)}
|
|
True
|
|
>>> getcallargs(f, a=2, x=4) == {'a': 2, 'named': {'x': 4}, 'b': 1, 'pos': ()}
|
|
True
|
|
>>> getcallargs(f)
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: f() missing 1 required positional argument: 'a'
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. deprecated:: 3.5
|
|
Use :meth:`Signature.bind` and :meth:`Signature.bind_partial` instead.
|
|
|
|
|
|
.. function:: getclosurevars(func)
|
|
|
|
Get the mapping of external name references in a Python function or
|
|
method *func* to their current values. A
|
|
:term:`named tuple` ``ClosureVars(nonlocals, globals, builtins, unbound)``
|
|
is returned. *nonlocals* maps referenced names to lexical closure
|
|
variables, *globals* to the function's module globals and *builtins* to
|
|
the builtins visible from the function body. *unbound* is the set of names
|
|
referenced in the function that could not be resolved at all given the
|
|
current module globals and builtins.
|
|
|
|
:exc:`TypeError` is raised if *func* is not a Python function or method.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
|
|
.. function:: unwrap(func, *, stop=None)
|
|
|
|
Get the object wrapped by *func*. It follows the chain of :attr:`__wrapped__`
|
|
attributes returning the last object in the chain.
|
|
|
|
*stop* is an optional callback accepting an object in the wrapper chain
|
|
as its sole argument that allows the unwrapping to be terminated early if
|
|
the callback returns a true value. If the callback never returns a true
|
|
value, the last object in the chain is returned as usual. For example,
|
|
:func:`signature` uses this to stop unwrapping if any object in the
|
|
chain has a ``__signature__`` attribute defined.
|
|
|
|
:exc:`ValueError` is raised if a cycle is encountered.
|
|
|
|
.. versionadded:: 3.4
|
|
|
|
|
|
.. function:: get_annotations(obj, *, globals=None, locals=None, eval_str=False)
|
|
|
|
Compute the annotations dict for an object.
|
|
|
|
``obj`` may be a callable, class, or module.
|
|
Passing in an object of any other type raises :exc:`TypeError`.
|
|
|
|
Returns a dict. ``get_annotations()`` returns a new dict every time
|
|
it's called; calling it twice on the same object will return two
|
|
different but equivalent dicts.
|
|
|
|
This function handles several details for you:
|
|
|
|
* If ``eval_str`` is true, values of type ``str`` will
|
|
be un-stringized using :func:`eval()`. This is intended
|
|
for use with stringized annotations
|
|
(``from __future__ import annotations``).
|
|
* If ``obj`` doesn't have an annotations dict, returns an
|
|
empty dict. (Functions and methods always have an
|
|
annotations dict; classes, modules, and other types of
|
|
callables may not.)
|
|
* Ignores inherited annotations on classes. If a class
|
|
doesn't have its own annotations dict, returns an empty dict.
|
|
* All accesses to object members and dict values are done
|
|
using ``getattr()`` and ``dict.get()`` for safety.
|
|
* Always, always, always returns a freshly created dict.
|
|
|
|
``eval_str`` controls whether or not values of type ``str`` are replaced
|
|
with the result of calling :func:`eval()` on those values:
|
|
|
|
* If eval_str is true, :func:`eval()` is called on values of type ``str``.
|
|
(Note that ``get_annotations`` doesn't catch exceptions; if :func:`eval()`
|
|
raises an exception, it will unwind the stack past the ``get_annotations``
|
|
call.)
|
|
* If eval_str is false (the default), values of type ``str`` are unchanged.
|
|
|
|
``globals`` and ``locals`` are passed in to :func:`eval()`; see the documentation
|
|
for :func:`eval()` for more information. If ``globals`` or ``locals``
|
|
is ``None``, this function may replace that value with a context-specific
|
|
default, contingent on ``type(obj)``:
|
|
|
|
* If ``obj`` is a module, ``globals`` defaults to ``obj.__dict__``.
|
|
* If ``obj`` is a class, ``globals`` defaults to
|
|
``sys.modules[obj.__module__].__dict__`` and ``locals`` defaults
|
|
to the ``obj`` class namespace.
|
|
* If ``obj`` is a callable, ``globals`` defaults to
|
|
:attr:`obj.__globals__ <function.__globals__>`,
|
|
although if ``obj`` is a wrapped function (using
|
|
:func:`functools.update_wrapper`) it is first unwrapped.
|
|
|
|
Calling ``get_annotations`` is best practice for accessing the
|
|
annotations dict of any object. See :ref:`annotations-howto` for
|
|
more information on annotations best practices.
|
|
|
|
.. versionadded:: 3.10
|
|
|
|
|
|
.. _inspect-stack:
|
|
|
|
The interpreter stack
|
|
---------------------
|
|
|
|
Some of the following functions return
|
|
:class:`FrameInfo` objects. For backwards compatibility these objects allow
|
|
tuple-like operations on all attributes except ``positions``. This behavior
|
|
is considered deprecated and may be removed in the future.
|
|
|
|
.. class:: FrameInfo
|
|
|
|
.. attribute:: frame
|
|
|
|
The :ref:`frame object <frame-objects>` that the record corresponds to.
|
|
|
|
.. attribute:: filename
|
|
|
|
The file name associated with the code being executed by the frame this record
|
|
corresponds to.
|
|
|
|
.. attribute:: lineno
|
|
|
|
The line number of the current line associated with the code being
|
|
executed by the frame this record corresponds to.
|
|
|
|
.. attribute:: function
|
|
|
|
The function name that is being executed by the frame this record corresponds to.
|
|
|
|
.. attribute:: code_context
|
|
|
|
A list of lines of context from the source code that's being executed by the frame
|
|
this record corresponds to.
|
|
|
|
.. attribute:: index
|
|
|
|
The index of the current line being executed in the :attr:`code_context` list.
|
|
|
|
.. attribute:: positions
|
|
|
|
A :class:`dis.Positions` object containing the start line number, end line
|
|
number, start column offset, and end column offset associated with the
|
|
instruction being executed by the frame this record corresponds to.
|
|
|
|
.. versionchanged:: 3.5
|
|
Return a :term:`named tuple` instead of a :class:`tuple`.
|
|
|
|
.. versionchanged:: 3.11
|
|
:class:`!FrameInfo` is now a class instance
|
|
(that is backwards compatible with the previous :term:`named tuple`).
|
|
|
|
|
|
.. class:: Traceback
|
|
|
|
.. attribute:: filename
|
|
|
|
The file name associated with the code being executed by the frame this traceback
|
|
corresponds to.
|
|
|
|
.. attribute:: lineno
|
|
|
|
The line number of the current line associated with the code being
|
|
executed by the frame this traceback corresponds to.
|
|
|
|
.. attribute:: function
|
|
|
|
The function name that is being executed by the frame this traceback corresponds to.
|
|
|
|
.. attribute:: code_context
|
|
|
|
A list of lines of context from the source code that's being executed by the frame
|
|
this traceback corresponds to.
|
|
|
|
.. attribute:: index
|
|
|
|
The index of the current line being executed in the :attr:`code_context` list.
|
|
|
|
.. attribute:: positions
|
|
|
|
A :class:`dis.Positions` object containing the start line number, end
|
|
line number, start column offset, and end column offset associated with
|
|
the instruction being executed by the frame this traceback corresponds
|
|
to.
|
|
|
|
.. versionchanged:: 3.11
|
|
:class:`!Traceback` is now a class instance
|
|
(that is backwards compatible with the previous :term:`named tuple`).
|
|
|
|
|
|
.. note::
|
|
|
|
Keeping references to frame objects, as found in the first element of the frame
|
|
records these functions return, can cause your program to create reference
|
|
cycles. Once a reference cycle has been created, the lifespan of all objects
|
|
which can be accessed from the objects which form the cycle can become much
|
|
longer even if Python's optional cycle detector is enabled. If such cycles must
|
|
be created, it is important to ensure they are explicitly broken to avoid the
|
|
delayed destruction of objects and increased memory consumption which occurs.
|
|
|
|
Though the cycle detector will catch these, destruction of the frames (and local
|
|
variables) can be made deterministic by removing the cycle in a
|
|
:keyword:`finally` clause. This is also important if the cycle detector was
|
|
disabled when Python was compiled or using :func:`gc.disable`. For example::
|
|
|
|
def handle_stackframe_without_leak():
|
|
frame = inspect.currentframe()
|
|
try:
|
|
# do something with the frame
|
|
finally:
|
|
del frame
|
|
|
|
If you want to keep the frame around (for example to print a traceback
|
|
later), you can also break reference cycles by using the
|
|
:meth:`frame.clear` method.
|
|
|
|
The optional *context* argument supported by most of these functions specifies
|
|
the number of lines of context to return, which are centered around the current
|
|
line.
|
|
|
|
|
|
.. function:: getframeinfo(frame, context=1)
|
|
|
|
Get information about a frame or traceback object. A :class:`Traceback` object
|
|
is returned.
|
|
|
|
.. versionchanged:: 3.11
|
|
A :class:`Traceback` object is returned instead of a named tuple.
|
|
|
|
.. function:: getouterframes(frame, context=1)
|
|
|
|
Get a list of :class:`FrameInfo` objects for a frame and all outer frames.
|
|
These frames represent the calls that lead to the creation of *frame*. The
|
|
first entry in the returned list represents *frame*; the last entry
|
|
represents the outermost call on *frame*'s stack.
|
|
|
|
.. versionchanged:: 3.5
|
|
A list of :term:`named tuples <named tuple>`
|
|
``FrameInfo(frame, filename, lineno, function, code_context, index)``
|
|
is returned.
|
|
|
|
.. versionchanged:: 3.11
|
|
A list of :class:`FrameInfo` objects is returned.
|
|
|
|
.. function:: getinnerframes(traceback, context=1)
|
|
|
|
Get a list of :class:`FrameInfo` objects for a traceback's frame and all
|
|
inner frames. These frames represent calls made as a consequence of *frame*.
|
|
The first entry in the list represents *traceback*; the last entry represents
|
|
where the exception was raised.
|
|
|
|
.. versionchanged:: 3.5
|
|
A list of :term:`named tuples <named tuple>`
|
|
``FrameInfo(frame, filename, lineno, function, code_context, index)``
|
|
is returned.
|
|
|
|
.. versionchanged:: 3.11
|
|
A list of :class:`FrameInfo` objects is returned.
|
|
|
|
.. function:: currentframe()
|
|
|
|
Return the frame object for the caller's stack frame.
|
|
|
|
.. impl-detail::
|
|
|
|
This function relies on Python stack frame support in the interpreter,
|
|
which isn't guaranteed to exist in all implementations of Python. If
|
|
running in an implementation without Python stack frame support this
|
|
function returns ``None``.
|
|
|
|
|
|
.. function:: stack(context=1)
|
|
|
|
Return a list of :class:`FrameInfo` objects for the caller's stack. The
|
|
first entry in the returned list represents the caller; the last entry
|
|
represents the outermost call on the stack.
|
|
|
|
.. versionchanged:: 3.5
|
|
A list of :term:`named tuples <named tuple>`
|
|
``FrameInfo(frame, filename, lineno, function, code_context, index)``
|
|
is returned.
|
|
|
|
.. versionchanged:: 3.11
|
|
A list of :class:`FrameInfo` objects is returned.
|
|
|
|
.. function:: trace(context=1)
|
|
|
|
Return a list of :class:`FrameInfo` objects for the stack between the current
|
|
frame and the frame in which an exception currently being handled was raised
|
|
in. The first entry in the list represents the caller; the last entry
|
|
represents where the exception was raised.
|
|
|
|
.. versionchanged:: 3.5
|
|
A list of :term:`named tuples <named tuple>`
|
|
``FrameInfo(frame, filename, lineno, function, code_context, index)``
|
|
is returned.
|
|
|
|
.. versionchanged:: 3.11
|
|
A list of :class:`FrameInfo` objects is returned.
|
|
|
|
Fetching attributes statically
|
|
------------------------------
|
|
|
|
Both :func:`getattr` and :func:`hasattr` can trigger code execution when
|
|
fetching or checking for the existence of attributes. Descriptors, like
|
|
properties, will be invoked and :meth:`~object.__getattr__` and
|
|
:meth:`~object.__getattribute__`
|
|
may be called.
|
|
|
|
For cases where you want passive introspection, like documentation tools, this
|
|
can be inconvenient. :func:`getattr_static` has the same signature as :func:`getattr`
|
|
but avoids executing code when it fetches attributes.
|
|
|
|
.. function:: getattr_static(obj, attr, default=None)
|
|
|
|
Retrieve attributes without triggering dynamic lookup via the
|
|
descriptor protocol, :meth:`~object.__getattr__`
|
|
or :meth:`~object.__getattribute__`.
|
|
|
|
Note: this function may not be able to retrieve all attributes
|
|
that getattr can fetch (like dynamically created attributes)
|
|
and may find attributes that getattr can't (like descriptors
|
|
that raise AttributeError). It can also return descriptors objects
|
|
instead of instance members.
|
|
|
|
If the instance :attr:`~object.__dict__` is shadowed by another member (for
|
|
example a property) then this function will be unable to find instance
|
|
members.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
:func:`getattr_static` does not resolve descriptors, for example slot descriptors or
|
|
getset descriptors on objects implemented in C. The descriptor object
|
|
is returned instead of the underlying attribute.
|
|
|
|
You can handle these with code like the following. Note that
|
|
for arbitrary getset descriptors invoking these may trigger
|
|
code execution::
|
|
|
|
# example code for resolving the builtin descriptor types
|
|
class _foo:
|
|
__slots__ = ['foo']
|
|
|
|
slot_descriptor = type(_foo.foo)
|
|
getset_descriptor = type(type(open(__file__)).name)
|
|
wrapper_descriptor = type(str.__dict__['__add__'])
|
|
descriptor_types = (slot_descriptor, getset_descriptor, wrapper_descriptor)
|
|
|
|
result = getattr_static(some_object, 'foo')
|
|
if type(result) in descriptor_types:
|
|
try:
|
|
result = result.__get__()
|
|
except AttributeError:
|
|
# descriptors can raise AttributeError to
|
|
# indicate there is no underlying value
|
|
# in which case the descriptor itself will
|
|
# have to do
|
|
pass
|
|
|
|
|
|
Current State of Generators, Coroutines, and Asynchronous Generators
|
|
--------------------------------------------------------------------
|
|
|
|
When implementing coroutine schedulers and for other advanced uses of
|
|
generators, it is useful to determine whether a generator is currently
|
|
executing, is waiting to start or resume or execution, or has already
|
|
terminated. :func:`getgeneratorstate` allows the current state of a
|
|
generator to be determined easily.
|
|
|
|
.. function:: getgeneratorstate(generator)
|
|
|
|
Get current state of a generator-iterator.
|
|
|
|
Possible states are:
|
|
|
|
* GEN_CREATED: Waiting to start execution.
|
|
* GEN_RUNNING: Currently being executed by the interpreter.
|
|
* GEN_SUSPENDED: Currently suspended at a yield expression.
|
|
* GEN_CLOSED: Execution has completed.
|
|
|
|
.. versionadded:: 3.2
|
|
|
|
.. function:: getcoroutinestate(coroutine)
|
|
|
|
Get current state of a coroutine object. The function is intended to be
|
|
used with coroutine objects created by :keyword:`async def` functions, but
|
|
will accept any coroutine-like object that has ``cr_running`` and
|
|
``cr_frame`` attributes.
|
|
|
|
Possible states are:
|
|
|
|
* CORO_CREATED: Waiting to start execution.
|
|
* CORO_RUNNING: Currently being executed by the interpreter.
|
|
* CORO_SUSPENDED: Currently suspended at an await expression.
|
|
* CORO_CLOSED: Execution has completed.
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
.. function:: getasyncgenstate(agen)
|
|
|
|
Get current state of an asynchronous generator object. The function is
|
|
intended to be used with asynchronous iterator objects created by
|
|
:keyword:`async def` functions which use the :keyword:`yield` statement,
|
|
but will accept any asynchronous generator-like object that has
|
|
``ag_running`` and ``ag_frame`` attributes.
|
|
|
|
Possible states are:
|
|
|
|
* AGEN_CREATED: Waiting to start execution.
|
|
* AGEN_RUNNING: Currently being executed by the interpreter.
|
|
* AGEN_SUSPENDED: Currently suspended at a yield expression.
|
|
* AGEN_CLOSED: Execution has completed.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
The current internal state of the generator can also be queried. This is
|
|
mostly useful for testing purposes, to ensure that internal state is being
|
|
updated as expected:
|
|
|
|
.. function:: getgeneratorlocals(generator)
|
|
|
|
Get the mapping of live local variables in *generator* to their current
|
|
values. A dictionary is returned that maps from variable names to values.
|
|
This is the equivalent of calling :func:`locals` in the body of the
|
|
generator, and all the same caveats apply.
|
|
|
|
If *generator* is a :term:`generator` with no currently associated frame,
|
|
then an empty dictionary is returned. :exc:`TypeError` is raised if
|
|
*generator* is not a Python generator object.
|
|
|
|
.. impl-detail::
|
|
|
|
This function relies on the generator exposing a Python stack frame
|
|
for introspection, which isn't guaranteed to be the case in all
|
|
implementations of Python. In such cases, this function will always
|
|
return an empty dictionary.
|
|
|
|
.. versionadded:: 3.3
|
|
|
|
.. function:: getcoroutinelocals(coroutine)
|
|
|
|
This function is analogous to :func:`~inspect.getgeneratorlocals`, but
|
|
works for coroutine objects created by :keyword:`async def` functions.
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
.. function:: getasyncgenlocals(agen)
|
|
|
|
This function is analogous to :func:`~inspect.getgeneratorlocals`, but
|
|
works for asynchronous generator objects created by :keyword:`async def`
|
|
functions which use the :keyword:`yield` statement.
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
|
|
.. _inspect-module-co-flags:
|
|
|
|
Code Objects Bit Flags
|
|
----------------------
|
|
|
|
Python code objects have a :attr:`~codeobject.co_flags` attribute,
|
|
which is a bitmap of the following flags:
|
|
|
|
.. data:: CO_OPTIMIZED
|
|
|
|
The code object is optimized, using fast locals.
|
|
|
|
.. data:: CO_NEWLOCALS
|
|
|
|
If set, a new dict will be created for the frame's :attr:`~frame.f_locals`
|
|
when the code object is executed.
|
|
|
|
.. data:: CO_VARARGS
|
|
|
|
The code object has a variable positional parameter (``*args``-like).
|
|
|
|
.. data:: CO_VARKEYWORDS
|
|
|
|
The code object has a variable keyword parameter (``**kwargs``-like).
|
|
|
|
.. data:: CO_NESTED
|
|
|
|
The flag is set when the code object is a nested function.
|
|
|
|
.. data:: CO_GENERATOR
|
|
|
|
The flag is set when the code object is a generator function, i.e.
|
|
a generator object is returned when the code object is executed.
|
|
|
|
.. data:: CO_COROUTINE
|
|
|
|
The flag is set when the code object is a coroutine function.
|
|
When the code object is executed it returns a coroutine object.
|
|
See :pep:`492` for more details.
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
.. data:: CO_ITERABLE_COROUTINE
|
|
|
|
The flag is used to transform generators into generator-based
|
|
coroutines. Generator objects with this flag can be used in
|
|
``await`` expression, and can ``yield from`` coroutine objects.
|
|
See :pep:`492` for more details.
|
|
|
|
.. versionadded:: 3.5
|
|
|
|
.. data:: CO_ASYNC_GENERATOR
|
|
|
|
The flag is set when the code object is an asynchronous generator
|
|
function. When the code object is executed it returns an
|
|
asynchronous generator object. See :pep:`525` for more details.
|
|
|
|
.. versionadded:: 3.6
|
|
|
|
.. note::
|
|
The flags are specific to CPython, and may not be defined in other
|
|
Python implementations. Furthermore, the flags are an implementation
|
|
detail, and can be removed or deprecated in future Python releases.
|
|
It's recommended to use public APIs from the :mod:`inspect` module
|
|
for any introspection needs.
|
|
|
|
|
|
Buffer flags
|
|
------------
|
|
|
|
.. class:: BufferFlags
|
|
|
|
This is an :class:`enum.IntFlag` that represents the flags that
|
|
can be passed to the :meth:`~object.__buffer__` method of objects
|
|
implementing the :ref:`buffer protocol <bufferobjects>`.
|
|
|
|
The meaning of the flags is explained at :ref:`buffer-request-types`.
|
|
|
|
.. attribute:: BufferFlags.SIMPLE
|
|
.. attribute:: BufferFlags.WRITABLE
|
|
.. attribute:: BufferFlags.FORMAT
|
|
.. attribute:: BufferFlags.ND
|
|
.. attribute:: BufferFlags.STRIDES
|
|
.. attribute:: BufferFlags.C_CONTIGUOUS
|
|
.. attribute:: BufferFlags.F_CONTIGUOUS
|
|
.. attribute:: BufferFlags.ANY_CONTIGUOUS
|
|
.. attribute:: BufferFlags.INDIRECT
|
|
.. attribute:: BufferFlags.CONTIG
|
|
.. attribute:: BufferFlags.CONTIG_RO
|
|
.. attribute:: BufferFlags.STRIDED
|
|
.. attribute:: BufferFlags.STRIDED_RO
|
|
.. attribute:: BufferFlags.RECORDS
|
|
.. attribute:: BufferFlags.RECORDS_RO
|
|
.. attribute:: BufferFlags.FULL
|
|
.. attribute:: BufferFlags.FULL_RO
|
|
.. attribute:: BufferFlags.READ
|
|
.. attribute:: BufferFlags.WRITE
|
|
|
|
.. versionadded:: 3.12
|
|
|
|
.. _inspect-module-cli:
|
|
|
|
Command Line Interface
|
|
----------------------
|
|
|
|
The :mod:`inspect` module also provides a basic introspection capability
|
|
from the command line.
|
|
|
|
.. program:: inspect
|
|
|
|
By default, accepts the name of a module and prints the source of that
|
|
module. A class or function within the module can be printed instead by
|
|
appended a colon and the qualified name of the target object.
|
|
|
|
.. option:: --details
|
|
|
|
Print information about the specified object rather than the source code
|