262 lines
11 KiB
TeX
262 lines
11 KiB
TeX
\section{\module{inspect} ---
|
|
Inspect live objects}
|
|
\declaremodule{standard}{inspect}
|
|
\modulesynopsis{Extract information and source code from live objects.}
|
|
\index{inspect}
|
|
|
|
\versionadded{2.1}
|
|
|
|
The \code{inspect} module provides several useful functions
|
|
to help get information about live objects such as modules,
|
|
classes, methods, functions, tracebacks, frame objects, and
|
|
code objects. For example, it can help you examine the
|
|
contents of a class, retrieve the source code of a method,
|
|
extract and format the argument list for a function, or
|
|
get all the information you need to display a detailed traceback.
|
|
|
|
There are four main kinds of services provided by this module:
|
|
type checking, getting source code, inspecting classes
|
|
and functions, and examining the interpreter stack.
|
|
|
|
\subsection{Types and members
|
|
\label{inspect-types}}
|
|
|
|
The \function{getmembers()} function retrieves the members
|
|
of an object such as a class or module.
|
|
The nine functions whose names begin with ``is'' are mainly
|
|
provided as convenient choices for the second argument to
|
|
\function{getmembers()}. They also help you determine when
|
|
you can expect to find the following special attributes:
|
|
|
|
\begin{tableiii}{c|l|l}{}{Type}{Attribute}{Description}
|
|
\lineiii{module}{__doc__}{documentation string}
|
|
\lineiii{}{__file__}{filename (missing for built-in modules)}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{class}{__doc__}{documentation string}
|
|
\lineiii{}{__module__}{name of module in which this class was defined}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{method}{__doc__}{documentation string}
|
|
\lineiii{}{__name__}{name with which this method was defined}
|
|
\lineiii{}{im_class}{class object in which this method belongs}
|
|
\lineiii{}{im_func}{function object containing implementation of method}
|
|
\lineiii{}{im_self}{instance to which this method is bound, or \code{None}}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{function}{__doc__}{documentation string}
|
|
\lineiii{}{__name__}{name with which this function was defined}
|
|
\lineiii{}{func_code}{code object containing compiled function bytecode}
|
|
\lineiii{}{func_defaults}{tuple of any default values for arguments}
|
|
\lineiii{}{func_doc}{(same as __doc__)}
|
|
\lineiii{}{func_globals}{global namespace in which this function was defined}
|
|
\lineiii{}{func_name}{(same as __name__)}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{traceback}{tb_frame}{frame object at this level}
|
|
\lineiii{}{tb_lasti}{index of last attempted instruction in bytecode}
|
|
\lineiii{}{tb_lineno}{current line number in Python source code}
|
|
\lineiii{}{tb_next}{next inner traceback object (called by this level)}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{frame}{f_back}{next outer frame object (this frame's caller)}
|
|
\lineiii{}{f_builtins}{built-in namespace seen by this frame}
|
|
\lineiii{}{f_code}{code object being executed in this frame}
|
|
\lineiii{}{f_exc_traceback}{traceback if raised in this frame, or \code{None}}
|
|
\lineiii{}{f_exc_type}{exception type if raised in this frame, or \code{None}}
|
|
\lineiii{}{f_exc_value}{exception value if raised in this frame, or \code{None}}
|
|
\lineiii{}{f_globals}{global namespace seen by this frame}
|
|
\lineiii{}{f_lasti}{index of last attempted instruction in bytecode}
|
|
\lineiii{}{f_lineno}{current line number in Python source code}
|
|
\lineiii{}{f_locals}{local namespace seen by this frame}
|
|
\lineiii{}{f_restricted}{0 or 1 if frame is in restricted execution mode}
|
|
\lineiii{}{f_trace}{tracing function for this frame, or \code{None}}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{code}{co_argcount}{number of arguments (not including * or ** args)}
|
|
\lineiii{}{co_code}{string of raw compiled bytecode}
|
|
\lineiii{}{co_consts}{tuple of constants used in the bytecode}
|
|
\lineiii{}{co_filename}{name of file in which this code object was created}
|
|
\lineiii{}{co_firstlineno}{number of first line in Python source code}
|
|
\lineiii{}{co_flags}{bitmap: 1=optimized \code{|} 2=newlocals \code{|} 4=*arg \code{|} 8=**arg}
|
|
\lineiii{}{co_lnotab}{encoded mapping of line numbers to bytecode indices}
|
|
\lineiii{}{co_name}{name with which this code object was defined}
|
|
\lineiii{}{co_names}{tuple of names of local variables}
|
|
\lineiii{}{co_nlocals}{number of local variables}
|
|
\lineiii{}{co_stacksize}{virtual machine stack space required}
|
|
\lineiii{}{co_varnames}{tuple of names of arguments and local variables}
|
|
\lineiii{}{}{}
|
|
|
|
\lineiii{builtin}{__doc__}{documentation string}
|
|
\lineiii{}{__name__}{original name of this function or method}
|
|
\lineiii{}{__self__}{instance to which a method is bound, or \code{None}}
|
|
\end{tableiii}
|
|
|
|
\begin{funcdesc}{getmembers}{object\optional{, predicate}}
|
|
Return all the members of an object in a list of (name, value) pairs
|
|
sorted by name. If the optional \var{predicate} argument is supplied,
|
|
only members for which the predicate returns a true value are included.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{ismodule}{object}
|
|
Return true if the object is a module.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{isclass}{object}
|
|
Return true if the object is a class.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{ismethod}{object}
|
|
Return true if the object is a method.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{isfunction}{object}
|
|
Return true if the object is a Python function or unnamed (lambda) function.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{istraceback}{object}
|
|
Return true if the object is a traceback.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{isframe}{object}
|
|
Return true if the object is a frame.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{iscode}{object}
|
|
Return true if the object is a code.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{isbuiltin}{object}
|
|
Return true if the object is a built-in function.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{isroutine}{object}
|
|
Return true if the object is a user-defined or built-in function or method.
|
|
\end{funcdesc}
|
|
|
|
\subsection{Retrieving source code
|
|
\label{inspect-source}}
|
|
|
|
\begin{funcdesc}{getdoc}{object}
|
|
Get the documentation string for an object.
|
|
All tabs are expanded to spaces. To clean up docstrings that are
|
|
indented to line up with blocks of code, any whitespace than can be
|
|
uniformly removed from the second line onwards is removed.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{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).
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getfile}{object}
|
|
Return the name of the (text or binary) file in which an object was defined.
|
|
This will fail with a TypeError if the object is a built-in module,
|
|
class, or function.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getmodule}{object}
|
|
Try to guess which module an object was defined in.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getsourcefile}{object}
|
|
Return the name of the Python source file in which an object was defined.
|
|
This will fail with a TypeError if the object is a built-in module,
|
|
class, or function.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{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 IOError is
|
|
raised if the source code cannot be retrieved.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{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
|
|
IOError is raised if the source code cannot be retrieved.
|
|
\end{funcdesc}
|
|
|
|
\subsection{Classes and functions
|
|
\label{inspect-classes-functions}}
|
|
|
|
\begin{funcdesc}{getclasstree}{classes\optional{, unique}}
|
|
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 \var{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.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getargspec}{func}
|
|
Get the names and default values of a function's arguments.
|
|
A tuple of four things is returned: (args, varargs, varkw, defaults).
|
|
\var{args} is a list of the argument names (it may contain nested lists).
|
|
\var{varargs} and \var{varkw} are the names of the * and ** arguments or
|
|
\code{None}.
|
|
\var{defaults} is a tuple of default argument values; if this tuple
|
|
has \var{n} elements, they correspond to the last \var{n} elements
|
|
listed in \var{args}.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getargvalues}{frame}
|
|
Get information about arguments passed into a particular frame.
|
|
A tuple of four things is returned: (args, varargs, varkw, locals).
|
|
\var{args} is a list of the argument names (it may contain nested lists).
|
|
\var{varargs} and \var{varkw} are the names of the * and ** arguments or
|
|
\code{None}.
|
|
\var{locals} is the locals dictionary of the given frame.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{formatargspec}{args\optional{, varargs, varkw, defaults,
|
|
argformat, varargsformat, varkwformat, defaultformat}}
|
|
Format a pretty argument spec from the four values returned by getargspec.
|
|
The other four arguments are the corresponding optional formatting functions
|
|
that are called to turn names and values into strings.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{formatargvalues}{args\optional{, varargs, varkw, locals,
|
|
argformat, varargsformat, varkwformat, valueformat}}
|
|
Format a pretty argument spec from the four values returned by getargvalues.
|
|
The other four arguments are the corresponding optional formatting functions
|
|
that are called to turn names and values into strings.
|
|
\end{funcdesc}
|
|
|
|
\subsection{The interpreter stack
|
|
\label{inspect-stack}}
|
|
|
|
When the following functions return ``frame records'', each record
|
|
is a tuple of six items: the frame object, the filename,
|
|
the line number of the current line, the function name, a list of
|
|
lines of context from the source code, and the index of the current
|
|
line within that list.
|
|
The optional \var{context} argument specifies the number of lines of
|
|
context to return, which are centered around the current line.
|
|
|
|
\begin{funcdesc}{getouterframes}{frame\optional{, context}}
|
|
Get a list of frame records for a frame and all higher (calling) frames.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{getinnerframes}{traceback\optional{, context}}
|
|
Get a list of frame records for a traceback's frame and all lower frames.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{currentframe}{}
|
|
Return the frame object for the caller's stack frame.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{stack}{\optional{context}}
|
|
Return a list of frame records for the stack above the caller's frame.
|
|
\end{funcdesc}
|
|
|
|
\begin{funcdesc}{trace}{\optional{context}}
|
|
Return a list of frame records for the stack below the current exception.
|
|
\end{funcdesc}
|