"""Get useful information from live Python objects.
This module encapsulates the interface provided by the internal special
attributes (co_*, im_*, tb_*, etc.) in a friendlier fashion.
It also provides some help for examining source code and class layout.
Here are some of the useful functions provided by this module:
ismodule(), isclass(), ismethod(), isfunction(), isgeneratorfunction(),
isgenerator(), istraceback(), isframe(), iscode(), isbuiltin(),
isroutine() - check object types
getmembers() - get members of an object that satisfy a given condition
getfile(), getsourcefile(), getsource() - find an object's source code
getdoc(), getcomments() - get documentation on an object
getmodule() - determine the module that an object came from
getclasstree() - arrange classes so as to represent their hierarchy
getargvalues(), getcallargs() - get info about function arguments
getfullargspec() - same, with support for Python 3 features
formatargspec(), formatargvalues() - format an argument spec
getouterframes(), getinnerframes() - get info about frames
currentframe() - get the current stack frame
stack(), trace() - get info about frames on the stack or in a traceback
signature() - get a Signature object for the callable
# This module is in the public domain. No warranties.
__author__ = ('Ka-Ping Yee <ping@lfw.org>',
'Yury Selivanov <yselivanov@sprymix.com>')
import importlib.machinery
from operator import attrgetter
from collections import namedtuple, OrderedDict
# Create constants for the compiler flags in Include/code.h
# We try to get them from dis to avoid duplication
for k, v in dis.COMPILER_FLAG_NAMES.items():
TPFLAGS_IS_ABSTRACT = 1 << 20
# ----------------------------------------------------------- type-checking
"""Return true if the object is a module.
Module objects provide these attributes:
__cached__ pathname to byte compiled file
__doc__ documentation string
__file__ filename (missing for built-in modules)"""
return isinstance(object, types.ModuleType)
"""Return true if the object is a class.
Class objects provide these attributes:
__doc__ documentation string
__module__ name of module in which this class was defined"""
return isinstance(object, type)
"""Return true if the object is an instance method.
Instance method objects provide these attributes:
__doc__ documentation string
__name__ name with which this method was defined
__func__ function object containing implementation of method
__self__ instance to which this method is bound"""
return isinstance(object, types.MethodType)
def ismethoddescriptor(object):
"""Return true if the object is a method descriptor.
But not if ismethod() or isclass() or isfunction() are true.
This is new in Python 2.2, and, for example, is true of int.__add__.
An object passing this test has a __get__ attribute but not a __set__
attribute, but beyond that the set of attributes varies. __name__ is
usually sensible, and __doc__ often is.
Methods implemented via descriptors that also pass one of the other
tests return false from the ismethoddescriptor() test, simply because
the other tests promise more -- you can, e.g., count on having the
__func__ attribute (etc) when an object passes ismethod()."""
if isclass(object) or ismethod(object) or isfunction(object):
return hasattr(tp, "__get__") and not hasattr(tp, "__set__")
def isdatadescriptor(object):
"""Return true if the object is a data descriptor.
Data descriptors have both a __get__ and a __set__ attribute. Examples are
properties (defined in Python) and getsets and members (defined in C).
Typically, data descriptors will also have __name__ and __doc__ attributes
(properties, getsets, and members have both of these attributes), but this
if isclass(object) or ismethod(object) or isfunction(object):
return hasattr(tp, "__set__") and hasattr(tp, "__get__")
if hasattr(types, 'MemberDescriptorType'):
def ismemberdescriptor(object):
"""Return true if the object is a member descriptor.
Member descriptors are specialized descriptors defined in extension
return isinstance(object, types.MemberDescriptorType)
def ismemberdescriptor(object):
"""Return true if the object is a member descriptor.
Member descriptors are specialized descriptors defined in extension
if hasattr(types, 'GetSetDescriptorType'):
def isgetsetdescriptor(object):
"""Return true if the object is a getset descriptor.
getset descriptors are specialized descriptors defined in extension
return isinstance(object, types.GetSetDescriptorType)
def isgetsetdescriptor(object):
"""Return true if the object is a getset descriptor.
getset descriptors are specialized descriptors defined in extension
"""Return true if the object is a user-defined function.
Function objects provide these attributes:
__doc__ documentation string
__name__ name with which this function was defined
__code__ code object containing compiled function bytecode
__defaults__ tuple of any default values for arguments
__globals__ global namespace in which this function was defined
__annotations__ dict of parameter annotations
__kwdefaults__ dict of keyword only parameters with defaults"""
return isinstance(object, types.FunctionType)
def isgeneratorfunction(object):
"""Return true if the object is a user-defined generator function.
Generator function objects provide the same attributes as functions.
See help(isfunction) for a list of attributes."""
return bool((isfunction(object) or ismethod(object)) and
object.__code__.co_flags & CO_GENERATOR)
def iscoroutinefunction(object):
"""Return true if the object is a coroutine function.
Coroutine functions are defined with "async def" syntax.
return bool((isfunction(object) or ismethod(object)) and
object.__code__.co_flags & CO_COROUTINE)
def isasyncgenfunction(object):
"""Return true if the object is an asynchronous generator function.
Asynchronous generator functions are defined with "async def"
syntax and have "yield" expressions in their body.
return bool((isfunction(object) or ismethod(object)) and
object.__code__.co_flags & CO_ASYNC_GENERATOR)
"""Return true if the object is an asynchronous generator."""
return isinstance(object, types.AsyncGeneratorType)
"""Return true if the object is a generator.
Generator objects provide these attributes:
__iter__ defined to support iteration over container
close raises a new GeneratorExit exception inside the
generator to terminate the iteration
gi_frame frame object or possibly None once the generator has
gi_running set to 1 when generator is executing, 0 otherwise
next return the next item from the container
send resumes the generator and "sends" a value that becomes
the result of the current yield-expression
throw used to raise an exception inside the generator"""
return isinstance(object, types.GeneratorType)
"""Return true if the object is a coroutine."""
return isinstance(object, types.CoroutineType)
"""Return true if object can be passed to an ``await`` expression."""
return (isinstance(object, types.CoroutineType) or
isinstance(object, types.GeneratorType) and
bool(object.gi_code.co_flags & CO_ITERABLE_COROUTINE) or
isinstance(object, collections.abc.Awaitable))
"""Return true if the object is a traceback.
Traceback objects provide these attributes:
tb_frame frame object at this level
tb_lasti index of last attempted instruction in bytecode
tb_lineno current line number in Python source code
tb_next next inner traceback object (called by this level)"""
return isinstance(object, types.TracebackType)
"""Return true if the object is a frame object.
Frame objects provide these attributes:
f_back next outer frame object (this frame's caller)
f_builtins built-in namespace seen by this frame
f_code code object being executed in this frame
f_globals global namespace seen by this frame
f_lasti index of last attempted instruction in bytecode
f_lineno current line number in Python source code
f_locals local namespace seen by this frame
f_trace tracing function for this frame, or None"""
return isinstance(object, types.FrameType)
"""Return true if the object is a code object.
Code objects provide these attributes:
co_argcount number of arguments (not including *, ** args
or keyword only arguments)
co_code string of raw compiled bytecode
co_cellvars tuple of names of cell variables
co_consts tuple of constants used in the bytecode
co_filename name of file in which this code object was created
co_firstlineno number of first line in Python source code
co_flags bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg
| 16=nested | 32=generator | 64=nofree | 128=coroutine
| 256=iterable_coroutine | 512=async_generator
co_freevars tuple of names of free variables
co_kwonlyargcount number of keyword only arguments (not including ** arg)
co_lnotab encoded mapping of line numbers to bytecode indices
co_name name with which this code object was defined
co_names tuple of names of local variables
co_nlocals number of local variables
co_stacksize virtual machine stack space required
co_varnames tuple of names of arguments and local variables"""
return isinstance(object, types.CodeType)
"""Return true if the object is a built-in function or method.
Built-in functions and methods provide these attributes:
__doc__ documentation string
__name__ original name of this function or method
__self__ instance to which a method is bound, or None"""
return isinstance(object, types.BuiltinFunctionType)
"""Return true if the object is any kind of function or method."""
return (isbuiltin(object)
or ismethoddescriptor(object))
"""Return true if the object is an abstract base class (ABC)."""
if not isinstance(object, type):
if object.__flags__ & TPFLAGS_IS_ABSTRACT:
if not issubclass(type(object), abc.ABCMeta):
if hasattr(object, '__abstractmethods__'):
# It looks like ABCMeta.__new__ has finished running;
# TPFLAGS_IS_ABSTRACT should have been accurate.
# It looks like ABCMeta.__new__ has not finished running yet; we're
# probably in __init_subclass__. We'll look for abstractmethods manually.
for name, value in object.__dict__.items():
if getattr(value, "__isabstractmethod__", False):
for base in object.__bases__:
for name in getattr(base, "__abstractmethods__", ()):
value = getattr(object, name, None)
if getattr(value, "__isabstractmethod__", False):
def getmembers(object, predicate=None):
"""Return all members of an object as (name, value) pairs sorted by name.
Optionally, only return members that satisfy a given predicate."""
mro = (object,) + getmro(object)
# :dd any DynamicClassAttributes to the list of names if object is a class;
# this may result in duplicate entries if, for example, a virtual
# attribute with the same name as a DynamicClassAttribute exists
for base in object.__bases__:
for k, v in base.__dict__.items():
if isinstance(v, types.DynamicClassAttribute):
# First try to get the value via getattr. Some descriptors don't
# like calling their __get__ (see bug #1785), so fall back to
# looking in the __dict__.
value = getattr(object, key)
# handle the duplicate key
value = base.__dict__[key]
# could be a (currently) missing slot member, or a buggy
# __dir__; discard and move on
if not predicate or predicate(value):
results.append((key, value))
results.sort(key=lambda pair: pair[0])
Attribute = namedtuple('Attribute', 'name kind defining_class object')
def classify_class_attrs(cls):
"""Return list of attribute-descriptor tuples.
For each name in dir(cls), the return list contains a 4-tuple
1. The kind of attribute this is, one of these strings:
'class method' created via classmethod()
'static method' created via staticmethod()
'property' created via property()
'method' any other flavor of method or descriptor
2. The class which defined this attribute (a class).
3. The object as obtained by calling getattr; if this fails, or if the
resulting object does not live anywhere in the class' mro (including
metaclasses) then the object is looked up in the defining class's
dict (found by walking the mro).
If one of the items in dir(cls) is stored in the metaclass it will now
be discovered and not have None be listed as the class in which it was
defined. Any items whose home class cannot be discovered are skipped.
metamro = getmro(type(cls)) # for attributes stored in the metaclass
metamro = tuple([cls for cls in metamro if cls not in (type, object)])
class_bases = (cls,) + mro
all_bases = class_bases + metamro
# :dd any DynamicClassAttributes to the list of names;
# this may result in duplicate entries if, for example, a virtual
# attribute with the same name as a DynamicClassAttribute exists.
for k, v in base.__dict__.items():
if isinstance(v, types.DynamicClassAttribute):
# Get the object associated with the name, and where it was defined.
# Normal objects will be looked up with both getattr and directly in
# its class' dict (in case getattr fails [bug #1785], and also to look
# For DynamicClassAttributes on the second pass we only look in the
# Getting an obj from the __dict__ sometimes reveals more than
# using getattr. Static and class methods are dramatic examples.
if name not in processed:
raise Exception("__dict__ is special, don't want the proxy")
get_obj = getattr(cls, name)
homecls = getattr(get_obj, "__objclass__", homecls)
if homecls not in class_bases:
# if the resulting object does not live somewhere in the
# mro, drop it and search the mro manually
# first look in the classes
for srch_cls in class_bases:
srch_obj = getattr(srch_cls, name, None)
# then check the metaclasses
srch_obj = srch_cls.__getattr__(cls, name)
if name in base.__dict__:
dict_obj = base.__dict__[name]
if homecls not in metamro:
# unable to locate the attribute anywhere, most likely due to
# buggy custom __dir__; discard and move on
obj = get_obj if get_obj is not None else dict_obj
# Classify the object or its descriptor.
if isinstance(dict_obj, staticmethod):
elif isinstance(dict_obj, classmethod):
elif isinstance(dict_obj, property):
result.append(Attribute(name, kind, homecls, obj))
# ----------------------------------------------------------- class helpers
"Return tuple of base classes (including cls) in method resolution order."
# -------------------------------------------------------- function helpers
def unwrap(func, *, stop=None):
"""Get the object wrapped by *func*.
Follows the chain of :attr:`__wrapped__` attributes returning the last
*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.
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
