Types and members

The :func:`getmembers` function retrieves the members of an object such as a class or module. The sixteen functions whose names begin with "is" are mainly provided as convenient choices for the second argument to :func:`getmembers`. They also help you determine when you can expect to find the following special attributes:

Note:

1. ?

   .. versionchanged:: 2.2
      :attr:`im_class` used to refer to the class that defined the method.
   
   
   

.. function:: getmembers(object[, predicate])

   Return all the members of an object in a list of (name, value) pairs sorted by
   name.  If the optional *predicate* argument is supplied, only members for which
   the predicate returns a true value are included.

   .. note::

      :func:`getmembers` does not return metaclass attributes when the argument
      is a class (this behavior is inherited from the :func:`dir` function).

.. function:: getmoduleinfo(path)

   Return a tuple of values that describe how Python will interpret the file
   identified by *path* if it is a module, or ``None`` if it would not be
   identified as a module.  The return tuple is ``(name, suffix, mode,
   module_type)``, where *name* is the name of the module without the name of
   any enclosing package, *suffix* is the trailing part of the file name (which
   may not be a dot-delimited extension), *mode* is the :func:`open` mode that
   would be used (``'r'`` or ``'rb'``), and *module_type* is an integer giving
   the type of the module.  *module_type* will have a value which can be
   compared to the constants defined in the :mod:`imp` module; see the
   documentation for that module for more information on module types.

   .. versionchanged:: 2.6
      Returns a :term:`named tuple` ``ModuleInfo(name, suffix, mode,
      module_type)``.

.. function:: getmodulename(path)

   Return the name of the module named by the file *path*, without including the
   names of enclosing packages.  This uses the same algorithm as the interpreter
   uses when searching for modules.  If the name cannot be matched according to the
   interpreter's rules, ``None`` is returned.

.. function:: ismodule(object)

   Return true if the object is a module.

.. function:: isclass(object)

   Return true if the object is a class, whether built-in or created in Python
   code.

.. function:: ismethod(object)

   Return true if the object is a bound method written in Python.

.. function:: isfunction(object)

   Return true if the object is a Python function, which includes functions
   created by a :term:`lambda` expression.

.. function:: isgeneratorfunction(object)

   Return true if the object is a Python generator function.

   .. versionadded:: 2.6

.. function:: isgenerator(object)

   Return true if the object is a generator.

   .. versionadded:: 2.6

.. function:: istraceback(object)

   Return true if the object is a traceback.

.. function:: isframe(object)

   Return true if the object is a frame.

.. function:: iscode(object)

   Return true if the object is a code.

.. function:: isbuiltin(object)

   Return true if the object is a built-in function or a bound built-in method.

.. function:: isroutine(object)

   Return true if the object is a user-defined or built-in function or method.

.. function:: isabstract(object)

   Return true if the object is an abstract base class.

   .. versionadded:: 2.6

.. function:: ismethoddescriptor(object)

   Return true if the object is a method descriptor, but not if
   :func:`ismethod`, :func:`isclass`, :func:`isfunction` or :func:`isbuiltin`
   are true.

   This is new as of Python 2.2, and, for example, is true of
   ``int.__add__``. An object passing this test has a :attr:`__get__` attribute
   but not a :attr:`__set__` attribute, but beyond that the set of attributes
   varies.  :attr:`__name__` is usually sensible, and :attr:`__doc__` often is.

   Methods implemented via descriptors that also pass one of the other tests
   return false from the :func:`ismethoddescriptor` test, simply because the
   other tests promise more -- you can, e.g., count on having the
   :attr:`im_func` attribute (etc) when an object passes :func:`ismethod`.

.. function:: isdatadescriptor(object)

   Return true if the object is a data descriptor.

   Data descriptors have both a :attr:`__get__` and a :attr:`__set__` attribute.
   Examples are properties (defined in Python), getsets, and members.  The
   latter two are defined in C and there are more specific tests available for
   those types, which is robust across Python implementations.  Typically, data
   descriptors will also have :attr:`__name__` and :attr:`__doc__` attributes
   (properties, getsets, and members have both of these attributes), but this is
   not guaranteed.

   .. versionadded:: 2.3

.. function:: isgetsetdescriptor(object)

   Return true if the object is a getset descriptor.

   .. impl-detail::

      getsets are attributes defined in extension modules via
      :c:type:`PyGetSetDef` structures.  For Python implementations without such
      types, this method will always return ``False``.

   .. versionadded:: 2.5

.. function:: ismemberdescriptor(object)

   Return true if the object is a member descriptor.

   .. impl-detail::

      Member descriptors are attributes defined in extension modules via
      :c:type:`PyMemberDef` structures.  For Python implementations without such
      types, this method will always return ``False``.

   .. versionadded:: 2.5

Retrieving source code

.. function:: getdoc(object)

   Get the documentation string for an object, cleaned up with :func:`cleandoc`.

.. 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).

.. 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.

.. function:: getsourcefile(object)

   Return the name of the Python source 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:: 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:`IOError` is raised if the source code cannot
   be retrieved.

.. 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:`IOError` is raised if the source code
   cannot be retrieved.

.. function:: cleandoc(doc)

   Clean up indentation from docstrings that are indented to line up with blocks
   of code.  Any whitespace that can be uniformly removed from the second line
   onwards is removed.  Also, all tabs are expanded to spaces.

   .. versionadded:: 2.6

Classes and functions

.. function:: getclasstree(classes[, 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 *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:: getargspec(func)

   Get the names and default values of a Python function's arguments. A tuple of
   four things is returned: ``(args, varargs, keywords, defaults)``. *args* is a
   list of the argument names (it may contain nested lists). *varargs* and
   *keywords* are the names of the ``*`` and ``**`` arguments or
   ``None``. *defaults* is a tuple of default argument values or None if there
   are no default arguments; if this tuple has *n* elements, they correspond to
   the last *n* elements listed in *args*.

   .. versionchanged:: 2.6
      Returns a :term:`named tuple` ``ArgSpec(args, varargs, keywords,
      defaults)``.

.. function:: getargvalues(frame)

   Get information about arguments passed into a particular frame. A tuple of
   four things is returned: ``(args, varargs, keywords, locals)``. *args* is a
   list of the argument names (it may contain nested lists). *varargs* and
   *keywords* are the names of the ``*`` and ``**`` arguments or ``None``.
   *locals* is the locals dictionary of the given frame.

   .. versionchanged:: 2.6
      Returns a :term:`named tuple` ``ArgInfo(args, varargs, keywords,
      locals)``.

.. function:: formatargspec(args[, varargs, varkw, defaults, formatarg, formatvarargs, formatvarkw, formatvalue, join])

   Format a pretty argument spec from the four values returned by
   :func:`getargspec`.  The format\* arguments are the corresponding optional
   formatting functions that are called to turn names and values into strings.

.. function:: formatargvalues(args[, varargs, varkw, locals, formatarg, formatvarargs, formatvarkw, formatvalue, join])

   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.

.. 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::

    >>> from inspect import getcallargs
    >>> def f(a, b=1, *pos, **named):
    ...     pass
    >>> getcallargs(f, 1, 2, 3)
    {'a': 1, 'named': {}, 'b': 2, 'pos': (3,)}
    >>> getcallargs(f, a=2, x=4)
    {'a': 2, 'named': {'x': 4}, 'b': 1, 'pos': ()}
    >>> getcallargs(f)
    Traceback (most recent call last):
    ...
    TypeError: f() takes at least 1 argument (0 given)

   .. versionadded:: 2.7

The interpreter 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.

def handle_stackframe_without_leak():
    frame = inspect.currentframe()
    try:
        # do something with the frame
    finally:
        del frame

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])

   Get information about a frame or traceback object.  A 5-tuple is returned, the
   last five elements of the frame's frame record.

   .. versionchanged:: 2.6
      Returns a :term:`named tuple` ``Traceback(filename, lineno, function,
      code_context, index)``.

.. function:: getouterframes(frame[, context])

   Get a list of frame records 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.

.. function:: getinnerframes(traceback[, context])

   Get a list of frame records 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.

.. 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])

   Return a list of frame records 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.

.. function:: trace([context])

   Return a list of frame records 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.