# -*- coding: iso-8859-1 -*-
"""Get useful information from live Python objects.
This module encapsulates the interface provided by the internal special
attributes (func_*, 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
getargspec(), getargvalues(), getcallargs() - get info about function arguments
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
# This module is in the public domain. No warranties.
__author__ = 'Ka-Ping Yee <ping@lfw.org>'
from operator import attrgetter
from collections import namedtuple
# These constants are from Include/code.h.
CO_OPTIMIZED, CO_NEWLOCALS, CO_VARARGS, CO_VARKEYWORDS = 0x1, 0x2, 0x4, 0x8
CO_NESTED, CO_GENERATOR, CO_NOFREE = 0x10, 0x20, 0x40
TPFLAGS_IS_ABSTRACT = 1 << 20
# ----------------------------------------------------------- type-checking
"""Return true if the object is a module.
Module objects provide these attributes:
__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, types.ClassType))
"""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
im_class class object in which this method belongs
im_func function object containing implementation of method
im_self instance to which this method is bound, or None"""
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
im_func attribute (etc) when an object passes ismethod()."""
return (hasattr(object, "__get__")
and not hasattr(object, "__set__") # else it's a data descriptor
and not ismethod(object) # mutual exclusion
and not isfunction(object)
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
return (hasattr(object, "__set__") and hasattr(object, "__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
func_code code object containing compiled function bytecode
func_defaults tuple of any default values for arguments
func_doc (same as __doc__)
func_globals global namespace in which this function was defined
func_name (same as __name__)"""
return isinstance(object, types.FunctionType)
def isgeneratorfunction(object):
"""Return true if the object is a user-defined generator function.
Generator function objects provides same attributes as functions.
See help(isfunction) for attributes listing."""
return bool((isfunction(object) or ismethod(object)) and
object.func_code.co_flags & CO_GENERATOR)
"""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 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_exc_traceback traceback if raised in this frame, or None
f_exc_type exception type if raised in this frame, or None
f_exc_value exception value if raised in this frame, or None
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_restricted 0 or 1 if frame is in restricted execution mode
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 * or ** args)
co_code string of raw compiled bytecode
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
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)."""
return bool(isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT)
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."""
value = getattr(object, key)
if not predicate or predicate(value):
results.append((key, value))
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
2. The class which defined this attribute (a class).
3. The object as obtained directly from the defining class's
__dict__, not via getattr. This is especially important for
data attributes: C.data is just a data object, but
C.__dict__['data'] may be a data descriptor with additional
info, like a __doc__ string.
# Get the object associated with the name, and where it was defined.
# Getting an obj from the __dict__ sometimes reveals more than
# using getattr. Static and class methods are dramatic examples.
# Furthermore, some objects may raise an Exception when fetched with
# getattr(). This is the case with some descriptors (bug #1785).
# Thus, we only use getattr() as a last resort.
for base in (cls,) + mro:
if name in base.__dict__:
obj = base.__dict__[name]
homecls = getattr(obj, "__objclass__", homecls)
if isinstance(obj, staticmethod):
elif isinstance(obj, classmethod):
elif isinstance(obj, property):
elif ismethoddescriptor(obj):
elif isdatadescriptor(obj):
obj_via_getattr = getattr(cls, name)
if (ismethod(obj_via_getattr) or
ismethoddescriptor(obj_via_getattr)):
result.append(Attribute(name, kind, homecls, obj))
# ----------------------------------------------------------- class helpers
def _searchbases(cls, accum):
# Simulate the "classic class" search order.
for base in cls.__bases__:
_searchbases(base, accum)
"Return tuple of base classes (including cls) in method resolution order."
if hasattr(cls, "__mro__"):
_searchbases(cls, result)
# -------------------------------------------------- source code extraction
"""Return the indent size, in spaces, at the start of a line of text."""
expline = string.expandtabs(line)
return len(expline) - len(string.lstrip(expline))
"""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."""
if not isinstance(doc, types.StringTypes):
"""Clean up indentation from docstrings.
Any whitespace that can be uniformly removed from the second line
lines = string.split(string.expandtabs(doc), '\n')
# Find minimum indentation of any non-blank lines after first line.
content = len(string.lstrip(line))
indent = len(line) - content
margin = min(margin, indent)
lines[0] = lines[0].lstrip()
for i in range(1, len(lines)): lines[i] = lines[i][margin:]
# Remove any trailing or leading blank lines.
while lines and not lines[-1]:
while lines and not lines[0]:
return string.join(lines, '\n')
"""Work out which source or compiled file an object was defined in."""
if hasattr(object, '__file__'):
raise TypeError('{!r} is a built-in module'.format(object))
object = sys.modules.get(object.__module__)
if hasattr(object, '__file__'):
raise TypeError('{!r} is a built-in class'.format(object))
object = object.func_code
return object.co_filename
raise TypeError('{!r} is not a module, class, method, '
'function, traceback, frame, or code object'.format(object))
ModuleInfo = namedtuple('ModuleInfo', 'name suffix mode module_type')
"""Get the module name, suffix, mode, and module type for a given file."""
filename = os.path.basename(path)
suffixes = map(lambda info:
(-len(info[0]), info[0], info[1], info[2]),
suffixes.sort() # try longest suffixes first, in case they overlap
for neglen, suffix, mode, mtype in suffixes:
if filename[neglen:] == suffix:
return ModuleInfo(filename[:neglen], suffix, mode, mtype)
"""Return the module name for a given file, or None."""
info = getmoduleinfo(path)
def getsourcefile(object):
"""Return the filename that can be used to locate an object's source.
Return None if no way can be identified to get the source.
filename = getfile(object)
if string.lower(filename[-4:]) in ('.pyc', '.pyo'):
filename = filename[:-4] + '.py'
for suffix, mode, kind in imp.get_suffixes():
if 'b' in mode and string.lower(filename[-len(suffix):]) == suffix:
# Looks like a binary file. We want to only return a text file.
if os.path.exists(filename):
# only return a non-existent filename if the module has a PEP 302 loader
if hasattr(getmodule(object, filename), '__loader__'):
# or it is in the linecache
if filename in linecache.cache:
def getabsfile(object, _filename=None):
"""Return an absolute path to the source or compiled file for an object.
The idea is for each object to have a unique origin, so this routine
normalizes the result as much as possible."""
_filename = getsourcefile(object) or getfile(object)
return os.path.normcase(os.path.abspath(_filename))
def getmodule(object, _filename=None):
"""Return the module an object was defined in, or None if not found."""
if hasattr(object, '__module__'):
return sys.modules.get(object.__module__)
# Try the filename to modulename cache
if _filename is not None and _filename in modulesbyfile:
return sys.modules.get(modulesbyfile[_filename])
# Try the cache again with the absolute file name
file = getabsfile(object, _filename)
if file in modulesbyfile:
return sys.modules.get(modulesbyfile[file])
# Update the filename to module name cache and check yet again
# Copy sys.modules in order to cope with changes while iterating
for modname, module in sys.modules.items():
if ismodule(module) and hasattr(module, '__file__'):
if f == _filesbymodname.get(modname, None):
# Have already mapped this module, so skip it
_filesbymodname[modname] = f
# Always map to the name the module knows itself by
modulesbyfile[f] = modulesbyfile[
os.path.realpath(f)] = module.__name__
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