cpython/Doc/c-api/code.rst

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.. highlight:: c
.. index:: object; code, code object
.. _codeobjects:
Code Objects
------------
.. sectionauthor:: Jeffrey Yasskin <jyasskin@gmail.com>
Code objects are a low-level detail of the CPython implementation.
Each one represents a chunk of executable code that hasn't yet been
bound into a function.
.. c:type:: PyCodeObject
The C structure of the objects used to describe code objects. The
fields of this type are subject to change at any time.
.. c:var:: PyTypeObject PyCode_Type
This is an instance of :c:type:`PyTypeObject` representing the Python
:class:`code` type.
.. c:function:: int PyCode_Check(PyObject *co)
Return true if *co* is a :class:`code` object. This function always succeeds.
.. c:function:: int PyCode_GetNumFree(PyCodeObject *co)
Return the number of free variables in *co*.
.. c:function:: PyCodeObject* PyCode_New(int argcount, int kwonlyargcount, int nlocals, int stacksize, int flags, PyObject *code, PyObject *consts, PyObject *names, PyObject *varnames, PyObject *freevars, PyObject *cellvars, PyObject *filename, PyObject *name, int firstlineno, PyObject *linetable, PyObject *exceptiontable)
Return a new code object. If you need a dummy code object to create a frame,
use :c:func:`PyCode_NewEmpty` instead. Calling :c:func:`PyCode_New` directly
will bind you to a precise Python version since the definition of the bytecode
changes often. The many arguments of this function are inter-dependent in complex
ways, meaning that subtle changes to values are likely to result in incorrect
execution or VM crashes. Use this function only with extreme care.
.. versionchanged:: 3.11
Added ``exceptiontable`` parameter.
.. c:function:: PyCodeObject* PyCode_NewWithPosOnlyArgs(int argcount, int posonlyargcount, int kwonlyargcount, int nlocals, int stacksize, int flags, PyObject *code, PyObject *consts, PyObject *names, PyObject *varnames, PyObject *freevars, PyObject *cellvars, PyObject *filename, PyObject *name, int firstlineno, PyObject *linetable, PyObject *exceptiontable)
Similar to :c:func:`PyCode_New`, but with an extra "posonlyargcount" for positional-only arguments.
The same caveats that apply to ``PyCode_New`` also apply to this function.
.. versionadded:: 3.8
.. versionchanged:: 3.11
Added ``exceptiontable`` parameter.
.. c:function:: PyCodeObject* PyCode_NewEmpty(const char *filename, const char *funcname, int firstlineno)
Return a new empty code object with the specified filename,
function name, and first line number. The resulting code
object will raise an ``Exception`` if executed.
.. c:function:: int PyCode_Addr2Line(PyCodeObject *co, int byte_offset)
Return the line number of the instruction that occurs on or before ``byte_offset`` and ends after it.
If you just need the line number of a frame, use :c:func:`PyFrame_GetLineNumber` instead.
For efficiently iterating over the line numbers in a code object, use `the API described in PEP 626
<https://peps.python.org/pep-0626/#out-of-process-debuggers-and-profilers>`_.
.. c:function:: int PyCode_Addr2Location(PyObject *co, int byte_offset, int *start_line, int *start_column, int *end_line, int *end_column)
Sets the passed ``int`` pointers to the source code line and column numbers
for the instruction at ``byte_offset``. Sets the value to ``0`` when
information is not available for any particular element.
Returns ``1`` if the function succeeds and 0 otherwise.
.. c:function:: PyObject* PyCode_GetCode(PyCodeObject *co)
Equivalent to the Python code ``getattr(co, 'co_code')``.
Returns a strong reference to a :c:type:`PyBytesObject` representing the
bytecode in a code object. On error, ``NULL`` is returned and an exception
is raised.
This ``PyBytesObject`` may be created on-demand by the interpreter and does
not necessarily represent the bytecode actually executed by CPython. The
primary use case for this function is debuggers and profilers.
.. versionadded:: 3.11
.. c:function:: PyObject* PyCode_GetVarnames(PyCodeObject *co)
Equivalent to the Python code ``getattr(co, 'co_varnames')``.
Returns a new reference to a :c:type:`PyTupleObject` containing the names of
the local variables. On error, ``NULL`` is returned and an exception
is raised.
.. versionadded:: 3.11
.. c:function:: PyObject* PyCode_GetCellvars(PyCodeObject *co)
Equivalent to the Python code ``getattr(co, 'co_cellvars')``.
Returns a new reference to a :c:type:`PyTupleObject` containing the names of
the local variables that are referenced by nested functions. On error, ``NULL``
is returned and an exception is raised.
.. versionadded:: 3.11
.. c:function:: PyObject* PyCode_GetFreevars(PyCodeObject *co)
Equivalent to the Python code ``getattr(co, 'co_freevars')``.
Returns a new reference to a :c:type:`PyTupleObject` containing the names of
the free variables. On error, ``NULL`` is returned and an exception is raised.
.. versionadded:: 3.11