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"""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
getargspec(), getargvalues(), getcallargs() - get info about function arguments
getfullargspec() - same, with support for Python-3000 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 imp
import importlib.machinery
import itertools
import linecache
import os
import re
import sys
import tokenize
import types
import warnings
import functools
import builtins
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, but fall
# back to hardcoding so the dependency is optional
try:
from dis import COMPILER_FLAG_NAMES as _flag_names
except ImportError:
CO_OPTIMIZED, CO_NEWLOCALS = 0x1, 0x2
CO_VARARGS, CO_VARKEYWORDS = 0x4, 0x8
CO_NESTED, CO_GENERATOR, CO_NOFREE = 0x10, 0x20, 0x40
else:
mod_dict = globals()
for k, v in _flag_names.items():
mod_dict["CO_" + v] = k
# See Include/object.h
TPFLAGS_IS_ABSTRACT = 1 << 20
# ----------------------------------------------------------- type-checking
def ismodule(object):
"""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)
def isclass(object):
"""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)
def ismethod(object):
"""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):
# mutual exclusion
return False
tp = type(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
is not guaranteed."""
if isclass(object) or ismethod(object) or isfunction(object):
# mutual exclusion
return False
tp = type(object)
return hasattr(tp, "__set__") and hasattr(tp, "__get__")
if hasattr(types, 'MemberDescriptorType'):
# CPython and equivalent
def ismemberdescriptor(object):
"""Return true if the object is a member descriptor.
Member descriptors are specialized descriptors defined in extension
modules."""
return isinstance(object, types.MemberDescriptorType)
else:
# Other implementations
def ismemberdescriptor(object):
"""Return true if the object is a member descriptor.
Member descriptors are specialized descriptors defined in extension
modules."""
return False
if hasattr(types, 'GetSetDescriptorType'):
# CPython and equivalent
def isgetsetdescriptor(object):
"""Return true if the object is a getset descriptor.
getset descriptors are specialized descriptors defined in extension
modules."""
return isinstance(object, types.GetSetDescriptorType)
else:
# Other implementations
def isgetsetdescriptor(object):
"""Return true if the object is a getset descriptor.
getset descriptors are specialized descriptors defined in extension
modules."""
return False
def isfunction(object):
"""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 provides same attributes as functions.
See help(isfunction) for attributes listing."""
return bool((isfunction(object) or ismethod(object)) and
object.__code__.co_flags & CO_GENERATOR)
def isgenerator(object):
"""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_code code object
gi_frame frame object or possibly None once the generator has
been exhausted
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)
def istraceback(object):
"""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)
def isframe(object):
"""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)
def iscode(object):
"""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)
def isbuiltin(object):
"""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)
def isroutine(object):
"""Return true if the object is any kind of function or method."""
return (isbuiltin(object)
or isfunction(object)
or ismethod(object)
or ismethoddescriptor(object))
def isabstract(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."""
if isclass(object):
mro = (object,) + getmro(object)
else:
mro = ()
results = []
for key in dir(object):
# First try to get the value via __dict__. Some descriptors don't
# like calling their __get__ (see bug #1785).
for base in mro:
if key in base.__dict__:
value = base.__dict__[key]
break
else:
try:
value = getattr(object, key)
except AttributeError:
continue
if not predicate or predicate(value):
results.append((key, value))
results.sort()
return results
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
with these elements:
0. The name (a string).
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
'data' not a 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.
"""
mro = getmro(cls)
names = dir(cls)
result = []
for name in names:
# 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.
homecls = None
for base in (cls,) + mro:
if name in base.__dict__:
obj = base.__dict__[name]
homecls = base
break
else:
obj = getattr(cls, name)
homecls = getattr(obj, "__objclass__", homecls)
# Classify the object.
if isinstance(obj, staticmethod):
kind = "static method"
elif isinstance(obj, classmethod):
kind = "class method"
elif isinstance(obj, property):
kind = "property"
elif ismethoddescriptor(obj):
kind = "method"
elif isdatadescriptor(obj):
kind = "data"
else:
obj_via_getattr = getattr(cls, name)
if (isfunction(obj_via_getattr) or
ismethoddescriptor(obj_via_getattr)):
kind = "method"
else:
kind = "data"
obj = obj_via_getattr
result.append(Attribute(name, kind, homecls, obj))
return result
# ----------------------------------------------------------- class helpers
def getmro(cls):
"Return tuple of base classes (including cls) in method resolution order."
return cls.__mro__
# -------------------------------------------------- source code extraction
def indentsize(line):
"""Return the indent size, in spaces, at the start of a line of text."""
expline = line.expandtabs()
return len(expline) - len(expline.lstrip())
def 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."""
try:
doc = object.__doc__
except AttributeError:
return None
if not isinstance(doc, str):
return None
return cleandoc(doc)
def cleandoc(doc):
"""Clean up indentation from docstrings.
Any whitespace that can be uniformly removed from the second line
onwards is removed."""
try:
lines = doc.expandtabs().split('\n')
except UnicodeError:
return None
else:
# Find minimum indentation of any non-blank lines after first line.
margin = sys.maxsize
for line in lines[1:]:
content = len(line.lstrip())
if content:
indent = len(line) - content
margin = min(margin, indent)
# Remove indentation.
if lines:
lines[0] = lines[0].lstrip()
if margin < sys.maxsize:
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]:
lines.pop()
while lines and not lines[0]:
lines.pop(0)
return '\n'.join(lines)
def getfile(object):
"""Work out which source or compiled file an object was defined in."""
if ismodule(object):
if hasattr(object, '__file__'):
return object.__file__
raise TypeError('{!r} is a built-in module'.format(object))
if isclass(object):
object = sys.modules.get(object.__module__)
if hasattr(object, '__file__'):
return object.__file__
raise TypeError('{!r} is a built-in class'.format(object))
if ismethod(object):
object = object.__func__
if isfunction(object):
object = object.__code__
if istraceback(object):
object = object.tb_frame
if isframe(object):
object = object.f_code
if iscode(object):
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')
def getmoduleinfo(path):
"""Get the module name, suffix, mode, and module type for a given file."""
warnings.warn('inspect.getmoduleinfo() is deprecated', DeprecationWarning,
2)
filename = os.path.basename(path)
suffixes = [(-len(suffix), suffix, mode, mtype)
for suffix, mode, mtype in imp.get_suffixes()]
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)
def getmodulename(path):
"""Return the module name for a given file, or None."""
fname = os.path.basename(path)
# Check for paths that look like an actual module file
suffixes = [(-len(suffix), suffix)
for suffix in importlib.machinery.all_suffixes()]
suffixes.sort() # try longest suffixes first, in case they overlap
for neglen, suffix in suffixes:
if fname.endswith(suffix):
return fname[:neglen]
return None
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)
all_bytecode_suffixes = importlib.machinery.DEBUG_BYTECODE_SUFFIXES[:]
all_bytecode_suffixes += importlib.machinery.OPTIMIZED_BYTECODE_SUFFIXES[:]
if any(filename.endswith(s) for s in all_bytecode_suffixes):
filename = (os.path.splitext(filename)[0] +
importlib.machinery.SOURCE_SUFFIXES[0])
elif any(filename.endswith(s) for s in
importlib.machinery.EXTENSION_SUFFIXES):
return None
if os.path.exists(filename):
return filename
# only return a non-existent filename if the module has a PEP 302 loader
if hasattr(getmodule(object, filename), '__loader__'):
return filename
# or it is in the linecache
if filename in linecache.cache:
return filename
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."""
if _filename is None:
_filename = getsourcefile(object) or getfile(object)
return os.path.normcase(os.path.abspath(_filename))
modulesbyfile = {}
_filesbymodname = {}
def getmodule(object, _filename=None):
"""Return the module an object was defined in, or None if not found."""
if ismodule(object):
return object
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
try:
file = getabsfile(object, _filename)
except TypeError:
return None
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 list(sys.modules.items()):
if ismodule(module) and hasattr(module, '__file__'):
f = module.__file__
if f == _filesbymodname.get(modname, None):
# Have already mapped this module, so skip it
continue
_filesbymodname[modname] = f
f = getabsfile(module)
# Always map to the name the module knows itself by
modulesbyfile[f] = modulesbyfile[
os.path.realpath(f)] = module.__name__
if file in modulesbyfile:
return sys.modules.get(modulesbyfile[file])
# Check the main module
main = sys.modules['__main__']
if not hasattr(object, '__name__'):
return None
if hasattr(main, object.__name__):
mainobject = getattr(main, object.__name__)
if mainobject is object:
return main
# Check builtins
builtin = sys.modules['builtins']
if hasattr(builtin, object.__name__):
builtinobject = getattr(builtin, object.__name__)
if builtinobject is object:
return builtin
def findsource(object):
"""Return the entire source file 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 all the lines
in the file and the line number indexes a line in that list. An IOError
is raised if the source code cannot be retrieved."""
file = getfile(object)
sourcefile = getsourcefile(object)
if not sourcefile and file[:1] + file[-1:] != '<>':
raise IOError('source code not available')
file = sourcefile if sourcefile else file
module = getmodule(object, file)
if module:
lines = linecache.getlines(file, module.__dict__)
else:
lines = linecache.getlines(file)
if not lines:
raise IOError('could not get source code')
if ismodule(object):
return lines, 0
if isclass(object):
name = object.__name__
pat = re.compile(r'^(\s*)class\s*' + name + r'\b')
# make some effort to find the best matching class definition:
# use the one with the least indentation, which is the one
# that's most probably not inside a function definition.
candidates = []
for i in range(len(lines)):
match = pat.match(lines[i])
if match:
# if it's at toplevel, it's already the best one
if lines[i][0] == 'c':
return lines, i
# else add whitespace to candidate list
candidates.append((match.group(1), i))
if candidates:
# this will sort by whitespace, and by line number,
# less whitespace first
candidates.sort()
return lines, candidates[0][1]
else:
raise IOError('could not find class definition')
if ismethod(object):
object = object.__func__
if isfunction(object):
object = object.__code__
if istraceback(object):
object = object.tb_frame
if isframe(object):
object = object.f_code
if iscode(object):
if not hasattr(object, 'co_firstlineno'):
raise IOError('could not find function definition')
lnum = object.co_firstlineno - 1
pat = re.compile(r'^(\s*def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
while lnum > 0:
if pat.match(lines[lnum]): break
lnum = lnum - 1
return lines, lnum
raise IOError('could not find code object')
def getcomments(object):
"""Get lines of comments immediately preceding an object's source code.
Returns None when source can't be found.
"""
try:
lines, lnum = findsource(object)
except (IOError, TypeError):
return None
if ismodule(object):
# Look for a comment block at the top of the file.
start = 0
if lines and lines[0][:2] == '#!': start = 1
while start < len(lines) and lines[start].strip() in ('', '#'):
start = start + 1
if start < len(lines) and lines[start][:1] == '#':
comments = []
end = start
while end < len(lines) and lines[end][:1] == '#':
comments.append(lines[end].expandtabs())
end = end + 1
return ''.join(comments)
# Look for a preceding block of comments at the same indentation.
elif lnum > 0:
indent = indentsize(lines[lnum])
end = lnum - 1
if end >= 0 and lines[end].lstrip()[:1] == '#' and \
indentsize(lines[end]) == indent:
comments = [lines[end].expandtabs().lstrip()]
if end > 0:
end = end - 1
comment = lines[end].expandtabs().lstrip()
while comment[:1] == '#' and indentsize(lines[end]) == indent:
comments[:0] = [comment]
end = end - 1
if end < 0: break
comment = lines[end].expandtabs().lstrip()
while comments and comments[0].strip() == '#':
comments[:1] = []
while comments and comments[-1].strip() == '#':
comments[-1:] = []
return ''.join(comments)
class EndOfBlock(Exception): pass
class BlockFinder:
"""Provide a tokeneater() method to detect the end of a code block."""
def __init__(self):
self.indent = 0
self.islambda = False
self.started = False
self.passline = False
self.last = 1
def tokeneater(self, type, token, srowcol, erowcol, line):
if not self.started:
# look for the first "def", "class" or "lambda"
if token in ("def", "class", "lambda"):
if token == "lambda":
self.islambda = True
self.started = True
self.passline = True # skip to the end of the line
elif type == tokenize.NEWLINE:
self.passline = False # stop skipping when a NEWLINE is seen
self.last = srowcol[0]
if self.islambda: # lambdas always end at the first NEWLINE
raise EndOfBlock
elif self.passline:
pass
elif type == tokenize.INDENT:
self.indent = self.indent + 1
self.passline = True
elif type == tokenize.DEDENT:
self.indent = self.indent - 1
# the end of matching indent/dedent pairs end a block
# (note that this only works for "def"/"class" blocks,
# not e.g. for "if: else:" or "try: finally:" blocks)
if self.indent <= 0:
raise EndOfBlock
elif self.indent == 0 and type not in (tokenize.COMMENT, tokenize.NL):
# any other token on the same indentation level end the previous
# block as well, except the pseudo-tokens COMMENT and NL.
raise EndOfBlock
def getblock(lines):
"""Extract the block of code at the top of the given list of lines."""
blockfinder = BlockFinder()
try:
tokens = tokenize.generate_tokens(iter(lines).__next__)
for _token in tokens:
blockfinder.tokeneater(*_token)
except (EndOfBlock, IndentationError):
pass
return lines[:blockfinder.last]
def 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."""
lines, lnum = findsource(object)
if ismodule(object): return lines, 0
else: return getblock(lines[lnum:]), lnum + 1
def 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."""
lines, lnum = getsourcelines(object)
return ''.join(lines)
# --------------------------------------------------- class tree extraction
def walktree(classes, children, parent):
"""Recursive helper function for getclasstree()."""
results = []
classes.sort(key=attrgetter('__module__', '__name__'))
for c in classes:
results.append((c, c.__bases__))
if c in children:
results.append(walktree(children[c], children, c))
return results
def getclasstree(classes, unique=False):
"""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."""
children = {}
roots = []
for c in classes:
if c.__bases__:
for parent in c.__bases__:
if not parent in children:
children[parent] = []
if c not in children[parent]:
children[parent].append(c)
if unique and parent in classes: break
elif c not in roots:
roots.append(c)
for parent in children:
if parent not in classes:
roots.append(parent)
return walktree(roots, children, None)
# ------------------------------------------------ argument list extraction
Arguments = namedtuple('Arguments', 'args, varargs, varkw')
def getargs(co):
"""Get information about the arguments accepted by a code object.
Three things are returned: (args, varargs, varkw), where
'args' is the list of argument names. Keyword-only arguments are
appended. 'varargs' and 'varkw' are the names of the * and **
arguments or None."""
args, varargs, kwonlyargs, varkw = _getfullargs(co)
return Arguments(args + kwonlyargs, varargs, varkw)
def _getfullargs(co):
"""Get information about the arguments accepted by a code object.
Four things are returned: (args, varargs, kwonlyargs, varkw), where
'args' and 'kwonlyargs' are lists of argument names, and 'varargs'
and 'varkw' are the names of the * and ** arguments or None."""
if not iscode(co):
raise TypeError('{!r} is not a code object'.format(co))
nargs = co.co_argcount
names = co.co_varnames
nkwargs = co.co_kwonlyargcount
args = list(names[:nargs])
kwonlyargs = list(names[nargs:nargs+nkwargs])
step = 0
nargs += nkwargs
varargs = None
if co.co_flags & CO_VARARGS:
varargs = co.co_varnames[nargs]
nargs = nargs + 1
varkw = None
if co.co_flags & CO_VARKEYWORDS:
varkw = co.co_varnames[nargs]
return args, varargs, kwonlyargs, varkw
ArgSpec = namedtuple('ArgSpec', 'args varargs keywords defaults')
def getargspec(func):
"""Get the names and default values of a function's arguments.
A tuple of four things is returned: (args, varargs, varkw, defaults).
'args' is a list of the argument names.
'args' will include keyword-only argument names.
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'defaults' is an n-tuple of the default values of the last n arguments.
Use the getfullargspec() API for Python-3000 code, as annotations
and keyword arguments are supported. getargspec() will raise ValueError
if the func has either annotations or keyword arguments.
"""
args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, ann = \
getfullargspec(func)
if kwonlyargs or ann:
raise ValueError("Function has keyword-only arguments or annotations"
", use getfullargspec() API which can support them")
return ArgSpec(args, varargs, varkw, defaults)
FullArgSpec = namedtuple('FullArgSpec',
'args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, annotations')
def getfullargspec(func):
"""Get the names and default values of a function's arguments.
A tuple of seven things is returned:
(args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults annotations).
'args' is a list of the argument names.
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'defaults' is an n-tuple of the default values of the last n arguments.
'kwonlyargs' is a list of keyword-only argument names.
'kwonlydefaults' is a dictionary mapping names from kwonlyargs to defaults.
'annotations' is a dictionary mapping argument names to annotations.
The first four items in the tuple correspond to getargspec().
"""
if ismethod(func):
func = func.__func__
if not isfunction(func):
raise TypeError('{!r} is not a Python function'.format(func))
args, varargs, kwonlyargs, varkw = _getfullargs(func.__code__)
return FullArgSpec(args, varargs, varkw, func.__defaults__,
kwonlyargs, func.__kwdefaults__, func.__annotations__)
ArgInfo = namedtuple('ArgInfo', 'args varargs keywords locals')
def getargvalues(frame):
"""Get information about arguments passed into a particular frame.
A tuple of four things is returned: (args, varargs, varkw, locals).
'args' is a list of the argument names.
'varargs' and 'varkw' are the names of the * and ** arguments or None.
'locals' is the locals dictionary of the given frame."""
args, varargs, varkw = getargs(frame.f_code)
return ArgInfo(args, varargs, varkw, frame.f_locals)
def formatannotation(annotation, base_module=None):
if isinstance(annotation, type):
if annotation.__module__ in ('builtins', base_module):
return annotation.__name__
return annotation.__module__+'.'+annotation.__name__
return repr(annotation)
def formatannotationrelativeto(object):
module = getattr(object, '__module__', None)
def _formatannotation(annotation):
return formatannotation(annotation, module)
return _formatannotation
def formatargspec(args, varargs=None, varkw=None, defaults=None,
kwonlyargs=(), kwonlydefaults={}, annotations={},
formatarg=str,
formatvarargs=lambda name: '*' + name,
formatvarkw=lambda name: '**' + name,
formatvalue=lambda value: '=' + repr(value),
formatreturns=lambda text: ' -> ' + text,
formatannotation=formatannotation):
"""Format an argument spec from the values returned by getargspec
or getfullargspec.
The first seven arguments are (args, varargs, varkw, defaults,
kwonlyargs, kwonlydefaults, annotations). The other five arguments
are the corresponding optional formatting functions that are called to
turn names and values into strings. The last argument is an optional
function to format the sequence of arguments."""
def formatargandannotation(arg):
result = formatarg(arg)
if arg in annotations:
result += ': ' + formatannotation(annotations[arg])
return result
specs = []
if defaults:
firstdefault = len(args) - len(defaults)
for i, arg in enumerate(args):
spec = formatargandannotation(arg)
if defaults and i >= firstdefault:
spec = spec + formatvalue(defaults[i - firstdefault])
specs.append(spec)
if varargs is not None:
specs.append(formatvarargs(formatargandannotation(varargs)))
else:
if kwonlyargs:
specs.append('*')
if kwonlyargs:
for kwonlyarg in kwonlyargs:
spec = formatargandannotation(kwonlyarg)
if kwonlydefaults and kwonlyarg in kwonlydefaults:
spec += formatvalue(kwonlydefaults[kwonlyarg])
specs.append(spec)
if varkw is not None:
specs.append(formatvarkw(formatargandannotation(varkw)))
result = '(' + ', '.join(specs) + ')'
if 'return' in annotations:
result += formatreturns(formatannotation(annotations['return']))
return result
def formatargvalues(args, varargs, varkw, locals,
formatarg=str,
formatvarargs=lambda name: '*' + name,
formatvarkw=lambda name: '**' + name,
formatvalue=lambda value: '=' + repr(value)):
"""Format an argument spec from the 4 values returned by getargvalues.
The first four arguments are (args, varargs, varkw, locals). The
next four arguments are the corresponding optional formatting functions
that are called to turn names and values into strings. The ninth
argument is an optional function to format the sequence of arguments."""
def convert(name, locals=locals,
formatarg=formatarg, formatvalue=formatvalue):
return formatarg(name) + formatvalue(locals[name])
specs = []
for i in range(len(args)):
specs.append(convert(args[i]))
if varargs:
specs.append(formatvarargs(varargs) + formatvalue(locals[varargs]))
if varkw:
specs.append(formatvarkw(varkw) + formatvalue(locals[varkw]))
return '(' + ', '.join(specs) + ')'
def _missing_arguments(f_name, argnames, pos, values):
names = [repr(name) for name in argnames if name not in values]
missing = len(names)
if missing == 1:
s = names[0]
elif missing == 2:
s = "{} and {}".format(*names)
else:
tail = ", {} and {}".format(names[-2:])
del names[-2:]
s = ", ".join(names) + tail
raise TypeError("%s() missing %i required %s argument%s: %s" %
(f_name, missing,
"positional" if pos else "keyword-only",
"" if missing == 1 else "s", s))
def _too_many(f_name, args, kwonly, varargs, defcount, given, values):
atleast = len(args) - defcount
kwonly_given = len([arg for arg in kwonly if arg in values])
if varargs:
plural = atleast != 1
sig = "at least %d" % (atleast,)
elif defcount:
plural = True
sig = "from %d to %d" % (atleast, len(args))
else:
plural = len(args) != 1
sig = str(len(args))
kwonly_sig = ""
if kwonly_given:
msg = " positional argument%s (and %d keyword-only argument%s)"
kwonly_sig = (msg % ("s" if given != 1 else "", kwonly_given,
"s" if kwonly_given != 1 else ""))
raise TypeError("%s() takes %s positional argument%s but %d%s %s given" %
(f_name, sig, "s" if plural else "", given, kwonly_sig,
"was" if given == 1 and not kwonly_given else "were"))
def getcallargs(*func_and_positional, **named):
"""Get the mapping of arguments to values.
A dict is returned, with keys the function argument names (including the
names of the * and ** arguments, if any), and values the respective bound
values from 'positional' and 'named'."""
func = func_and_positional[0]
positional = func_and_positional[1:]
spec = getfullargspec(func)
args, varargs, varkw, defaults, kwonlyargs, kwonlydefaults, ann = spec
f_name = func.__name__
arg2value = {}
if ismethod(func) and func.__self__ is not None:
# implicit 'self' (or 'cls' for classmethods) argument
positional = (func.__self__,) + positional
num_pos = len(positional)
num_args = len(args)
num_defaults = len(defaults) if defaults else 0
n = min(num_pos, num_args)
for i in range(n):
arg2value[args[i]] = positional[i]
if varargs:
arg2value[varargs] = tuple(positional[n:])
possible_kwargs = set(args + kwonlyargs)
if varkw:
arg2value[varkw] = {}
for kw, value in named.items():
if kw not in possible_kwargs:
if not varkw:
raise TypeError("%s() got an unexpected keyword argument %r" %
(f_name, kw))
arg2value[varkw][kw] = value
continue
if kw in arg2value:
raise TypeError("%s() got multiple values for argument %r" %
(f_name, kw))
arg2value[kw] = value
if num_pos > num_args and not varargs:
_too_many(f_name, args, kwonlyargs, varargs, num_defaults,
num_pos, arg2value)
if num_pos < num_args:
req = args[:num_args - num_defaults]
for arg in req:
if arg not in arg2value:
_missing_arguments(f_name, req, True, arg2value)
for i, arg in enumerate(args[num_args - num_defaults:]):
if arg not in arg2value:
arg2value[arg] = defaults[i]
missing = 0
for kwarg in kwonlyargs:
if kwarg not in arg2value:
if kwarg in kwonlydefaults:
arg2value[kwarg] = kwonlydefaults[kwarg]
else:
missing += 1
if missing:
_missing_arguments(f_name, kwonlyargs, False, arg2value)
return arg2value
ClosureVars = namedtuple('ClosureVars', 'nonlocals globals builtins unbound')
def getclosurevars(func):
"""
Get the mapping of free variables to their current values.
Returns a named tuple of dicts mapping the current nonlocal, global
and builtin references as seen by the body of the function. A final
set of unbound names that could not be resolved is also provided.
"""
if ismethod(func):
func = func.__func__
if not isfunction(func):
raise TypeError("'{!r}' is not a Python function".format(func))
code = func.__code__
# Nonlocal references are named in co_freevars and resolved
# by looking them up in __closure__ by positional index
if func.__closure__ is None:
nonlocal_vars = {}
else:
nonlocal_vars = {
var : cell.cell_contents
for var, cell in zip(code.co_freevars, func.__closure__)
}
# Global and builtin references are named in co_names and resolved
# by looking them up in __globals__ or __builtins__
global_ns = func.__globals__
builtin_ns = global_ns.get("__builtins__", builtins.__dict__)
if ismodule(builtin_ns):
builtin_ns = builtin_ns.__dict__
global_vars = {}
builtin_vars = {}
unbound_names = set()
for name in code.co_names:
if name in ("None", "True", "False"):
# Because these used to be builtins instead of keywords, they
# may still show up as name references. We ignore them.
continue
try:
global_vars[name] = global_ns[name]
except KeyError:
try:
builtin_vars[name] = builtin_ns[name]
except KeyError:
unbound_names.add(name)
return ClosureVars(nonlocal_vars, global_vars,
builtin_vars, unbound_names)
# -------------------------------------------------- stack frame extraction
Traceback = namedtuple('Traceback', 'filename lineno function code_context index')
def getframeinfo(frame, context=1):
"""Get information about a frame or traceback object.
A tuple of five things is returned: 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 second argument specifies the number of lines of context
to return, which are centered around the current line."""
if istraceback(frame):
lineno = frame.tb_lineno
frame = frame.tb_frame
else:
lineno = frame.f_lineno
if not isframe(frame):
raise TypeError('{!r} is not a frame or traceback object'.format(frame))
filename = getsourcefile(frame) or getfile(frame)
if context > 0:
start = lineno - 1 - context//2
try:
lines, lnum = findsource(frame)
except IOError:
lines = index = None
else:
start = max(start, 1)
start = max(0, min(start, len(lines) - context))
lines = lines[start:start+context]
index = lineno - 1 - start
else:
lines = index = None
return Traceback(filename, lineno, frame.f_code.co_name, lines, index)
def getlineno(frame):
"""Get the line number from a frame object, allowing for optimization."""
# FrameType.f_lineno is now a descriptor that grovels co_lnotab
return frame.f_lineno
def getouterframes(frame, context=1):
"""Get a list of records for a frame and all higher (calling) frames.
Each record contains a frame object, filename, line number, function
name, a list of lines of context, and index within the context."""
framelist = []
while frame:
framelist.append((frame,) + getframeinfo(frame, context))
frame = frame.f_back
return framelist
def getinnerframes(tb, context=1):
"""Get a list of records for a traceback's frame and all lower frames.
Each record contains a frame object, filename, line number, function
name, a list of lines of context, and index within the context."""
framelist = []
while tb:
framelist.append((tb.tb_frame,) + getframeinfo(tb, context))
tb = tb.tb_next
return framelist
def currentframe():
"""Return the frame of the caller or None if this is not possible."""
return sys._getframe(1) if hasattr(sys, "_getframe") else None
def stack(context=1):
"""Return a list of records for the stack above the caller's frame."""
return getouterframes(sys._getframe(1), context)
def trace(context=1):
"""Return a list of records for the stack below the current exception."""
return getinnerframes(sys.exc_info()[2], context)
# ------------------------------------------------ static version of getattr
_sentinel = object()
def _static_getmro(klass):
return type.__dict__['__mro__'].__get__(klass)
def _check_instance(obj, attr):
instance_dict = {}
try:
instance_dict = object.__getattribute__(obj, "__dict__")
except AttributeError:
pass
return dict.get(instance_dict, attr, _sentinel)
def _check_class(klass, attr):
for entry in _static_getmro(klass):
if _shadowed_dict(type(entry)) is _sentinel:
try:
return entry.__dict__[attr]
except KeyError:
pass
return _sentinel
def _is_type(obj):
try:
_static_getmro(obj)
except TypeError:
return False
return True
def _shadowed_dict(klass):
dict_attr = type.__dict__["__dict__"]
for entry in _static_getmro(klass):
try:
class_dict = dict_attr.__get__(entry)["__dict__"]
except KeyError:
pass
else:
if not (type(class_dict) is types.GetSetDescriptorType and
class_dict.__name__ == "__dict__" and
class_dict.__objclass__ is entry):
return class_dict
return _sentinel
def getattr_static(obj, attr, default=_sentinel):
"""Retrieve attributes without triggering dynamic lookup via the
descriptor protocol, __getattr__ or __getattribute__.
Note: this function may not be able to retrieve all attributes
that getattr can fetch (like dynamically created attributes)
and may find attributes that getattr can't (like descriptors
that raise AttributeError). It can also return descriptor objects
instead of instance members in some cases. See the
documentation for details.
"""
instance_result = _sentinel
if not _is_type(obj):
klass = type(obj)
dict_attr = _shadowed_dict(klass)
if (dict_attr is _sentinel or
type(dict_attr) is types.MemberDescriptorType):
instance_result = _check_instance(obj, attr)
else:
klass = obj
klass_result = _check_class(klass, attr)
if instance_result is not _sentinel and klass_result is not _sentinel:
if (_check_class(type(klass_result), '__get__') is not _sentinel and
_check_class(type(klass_result), '__set__') is not _sentinel):
return klass_result
if instance_result is not _sentinel:
return instance_result
if klass_result is not _sentinel:
return klass_result
if obj is klass:
# for types we check the metaclass too
for entry in _static_getmro(type(klass)):
if _shadowed_dict(type(entry)) is _sentinel:
try:
return entry.__dict__[attr]
except KeyError:
pass
if default is not _sentinel:
return default
raise AttributeError(attr)
# ------------------------------------------------ generator introspection
GEN_CREATED = 'GEN_CREATED'
GEN_RUNNING = 'GEN_RUNNING'
GEN_SUSPENDED = 'GEN_SUSPENDED'
GEN_CLOSED = 'GEN_CLOSED'
def getgeneratorstate(generator):
"""Get current state of a generator-iterator.
Possible states are:
GEN_CREATED: Waiting to start execution.
GEN_RUNNING: Currently being executed by the interpreter.
GEN_SUSPENDED: Currently suspended at a yield expression.
GEN_CLOSED: Execution has completed.
"""
if generator.gi_running:
return GEN_RUNNING
if generator.gi_frame is None:
return GEN_CLOSED
if generator.gi_frame.f_lasti == -1:
return GEN_CREATED
return GEN_SUSPENDED
def getgeneratorlocals(generator):
"""
Get the mapping of generator local variables to their current values.
A dict is returned, with the keys the local variable names and values the
bound values."""
if not isgenerator(generator):
raise TypeError("'{!r}' is not a Python generator".format(generator))
frame = getattr(generator, "gi_frame", None)
if frame is not None:
return generator.gi_frame.f_locals
else:
return {}
###############################################################################
### Function Signature Object (PEP 362)
###############################################################################
_WrapperDescriptor = type(type.__call__)
_MethodWrapper = type(all.__call__)
_NonUserDefinedCallables = (_WrapperDescriptor,
_MethodWrapper,
types.BuiltinFunctionType)
def _get_user_defined_method(cls, method_name):
try:
meth = getattr(cls, method_name)
except AttributeError:
return
else:
if not isinstance(meth, _NonUserDefinedCallables):
# Once '__signature__' will be added to 'C'-level
# callables, this check won't be necessary
return meth
def signature(obj):
'''Get a signature object for the passed callable.'''
if not callable(obj):
raise TypeError('{!r} is not a callable object'.format(obj))
if isinstance(obj, types.MethodType):
# In this case we skip the first parameter of the underlying
# function (usually `self` or `cls`).
sig = signature(obj.__func__)
return sig.replace(parameters=tuple(sig.parameters.values())[1:])
try:
sig = obj.__signature__
except AttributeError:
pass
else:
if sig is not None:
return sig
try:
# Was this function wrapped by a decorator?
wrapped = obj.__wrapped__
except AttributeError:
pass
else:
return signature(wrapped)
if isinstance(obj, types.FunctionType):
return Signature.from_function(obj)
if isinstance(obj, functools.partial):
sig = signature(obj.func)
new_params = OrderedDict(sig.parameters.items())
partial_args = obj.args or ()
partial_keywords = obj.keywords or {}
try:
ba = sig.bind_partial(*partial_args, **partial_keywords)
except TypeError as ex:
msg = 'partial object {!r} has incorrect arguments'.format(obj)
raise ValueError(msg) from ex
for arg_name, arg_value in ba.arguments.items():
param = new_params[arg_name]
if arg_name in partial_keywords:
# We set a new default value, because the following code
# is correct:
#
# >>> def foo(a): print(a)
# >>> print(partial(partial(foo, a=10), a=20)())
# 20
# >>> print(partial(partial(foo, a=10), a=20)(a=30))
# 30
#
# So, with 'partial' objects, passing a keyword argument is
# like setting a new default value for the corresponding
# parameter
#
# We also mark this parameter with '_partial_kwarg'
# flag. Later, in '_bind', the 'default' value of this
# parameter will be added to 'kwargs', to simulate
# the 'functools.partial' real call.
new_params[arg_name] = param.replace(default=arg_value,
_partial_kwarg=True)
elif (param.kind not in (_VAR_KEYWORD, _VAR_POSITIONAL) and
not param._partial_kwarg):
new_params.pop(arg_name)
return sig.replace(parameters=new_params.values())
sig = None
if isinstance(obj, type):
# obj is a class or a metaclass
# First, let's see if it has an overloaded __call__ defined
# in its metaclass
call = _get_user_defined_method(type(obj), '__call__')
if call is not None:
sig = signature(call)
else:
# Now we check if the 'obj' class has a '__new__' method
new = _get_user_defined_method(obj, '__new__')
if new is not None:
sig = signature(new)
else:
# Finally, we should have at least __init__ implemented
init = _get_user_defined_method(obj, '__init__')
if init is not None:
sig = signature(init)
elif not isinstance(obj, _NonUserDefinedCallables):
# An object with __call__
# We also check that the 'obj' is not an instance of
# _WrapperDescriptor or _MethodWrapper to avoid
# infinite recursion (and even potential segfault)
call = _get_user_defined_method(type(obj), '__call__')
if call is not None:
sig = signature(call)
if sig is not None:
# For classes and objects we skip the first parameter of their
# __call__, __new__, or __init__ methods
return sig.replace(parameters=tuple(sig.parameters.values())[1:])
if isinstance(obj, types.BuiltinFunctionType):
# Raise a nicer error message for builtins
msg = 'no signature found for builtin function {!r}'.format(obj)
raise ValueError(msg)
raise ValueError('callable {!r} is not supported by signature'.format(obj))
class _void:
'''A private marker - used in Parameter & Signature'''
class _empty:
pass
class _ParameterKind(int):
def __new__(self, *args, name):
obj = int.__new__(self, *args)
obj._name = name
return obj
def __str__(self):
return self._name
def __repr__(self):
return '<_ParameterKind: {!r}>'.format(self._name)
_POSITIONAL_ONLY = _ParameterKind(0, name='POSITIONAL_ONLY')
_POSITIONAL_OR_KEYWORD = _ParameterKind(1, name='POSITIONAL_OR_KEYWORD')
_VAR_POSITIONAL = _ParameterKind(2, name='VAR_POSITIONAL')
_KEYWORD_ONLY = _ParameterKind(3, name='KEYWORD_ONLY')
_VAR_KEYWORD = _ParameterKind(4, name='VAR_KEYWORD')
class Parameter:
'''Represents a parameter in a function signature.
Has the following public attributes:
* name : str
The name of the parameter as a string.
* default : object
The default value for the parameter if specified. If the
parameter has no default value, this attribute is not set.
* annotation
The annotation for the parameter if specified. If the
parameter has no annotation, this attribute is not set.
* kind : str
Describes how argument values are bound to the parameter.
Possible values: `Parameter.POSITIONAL_ONLY`,
`Parameter.POSITIONAL_OR_KEYWORD`, `Parameter.VAR_POSITIONAL`,
`Parameter.KEYWORD_ONLY`, `Parameter.VAR_KEYWORD`.
'''
__slots__ = ('_name', '_kind', '_default', '_annotation', '_partial_kwarg')
POSITIONAL_ONLY = _POSITIONAL_ONLY
POSITIONAL_OR_KEYWORD = _POSITIONAL_OR_KEYWORD
VAR_POSITIONAL = _VAR_POSITIONAL
KEYWORD_ONLY = _KEYWORD_ONLY
VAR_KEYWORD = _VAR_KEYWORD
empty = _empty
def __init__(self, name, kind, *, default=_empty, annotation=_empty,
_partial_kwarg=False):
if kind not in (_POSITIONAL_ONLY, _POSITIONAL_OR_KEYWORD,
_VAR_POSITIONAL, _KEYWORD_ONLY, _VAR_KEYWORD):
raise ValueError("invalid value for 'Parameter.kind' attribute")
self._kind = kind
if default is not _empty:
if kind in (_VAR_POSITIONAL, _VAR_KEYWORD):
msg = '{} parameters cannot have default values'.format(kind)
raise ValueError(msg)
self._default = default
self._annotation = annotation
if name is None:
if kind != _POSITIONAL_ONLY:
raise ValueError("None is not a valid name for a "
"non-positional-only parameter")
self._name = name
else:
name = str(name)
if kind != _POSITIONAL_ONLY and not name.isidentifier():
msg = '{!r} is not a valid parameter name'.format(name)
raise ValueError(msg)
self._name = name
self._partial_kwarg = _partial_kwarg
@property
def name(self):
return self._name
@property
def default(self):
return self._default
@property
def annotation(self):
return self._annotation
@property
def kind(self):
return self._kind
def replace(self, *, name=_void, kind=_void, annotation=_void,
default=_void, _partial_kwarg=_void):
'''Creates a customized copy of the Parameter.'''
if name is _void:
name = self._name
if kind is _void:
kind = self._kind
if annotation is _void:
annotation = self._annotation
if default is _void:
default = self._default
if _partial_kwarg is _void:
_partial_kwarg = self._partial_kwarg
return type(self)(name, kind, default=default, annotation=annotation,
_partial_kwarg=_partial_kwarg)
def __str__(self):
kind = self.kind
formatted = self._name
if kind == _POSITIONAL_ONLY:
if formatted is None:
formatted = ''
formatted = '<{}>'.format(formatted)
# Add annotation and default value
if self._annotation is not _empty:
formatted = '{}:{}'.format(formatted,
formatannotation(self._annotation))
if self._default is not _empty:
formatted = '{}={}'.format(formatted, repr(self._default))
if kind == _VAR_POSITIONAL:
formatted = '*' + formatted
elif kind == _VAR_KEYWORD:
formatted = '**' + formatted
return formatted
def __repr__(self):
return '<{} at {:#x} {!r}>'.format(self.__class__.__name__,
id(self), self.name)
def __eq__(self, other):
return (issubclass(other.__class__, Parameter) and
self._name == other._name and
self._kind == other._kind and
self._default == other._default and
self._annotation == other._annotation)
def __ne__(self, other):
return not self.__eq__(other)
class BoundArguments:
'''Result of `Signature.bind` call. Holds the mapping of arguments
to the function's parameters.
Has the following public attributes:
* arguments : OrderedDict
An ordered mutable mapping of parameters' names to arguments' values.
Does not contain arguments' default values.
* signature : Signature
The Signature object that created this instance.
* args : tuple
Tuple of positional arguments values.
* kwargs : dict
Dict of keyword arguments values.
'''
def __init__(self, signature, arguments):
self.arguments = arguments
self._signature = signature
@property
def signature(self):
return self._signature
@property
def args(self):
args = []
for param_name, param in self._signature.parameters.items():
if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
param._partial_kwarg):
# Keyword arguments mapped by 'functools.partial'
# (Parameter._partial_kwarg is True) are mapped
# in 'BoundArguments.kwargs', along with VAR_KEYWORD &
# KEYWORD_ONLY
break
try:
arg = self.arguments[param_name]
except KeyError:
# We're done here. Other arguments
# will be mapped in 'BoundArguments.kwargs'
break
else:
if param.kind == _VAR_POSITIONAL:
# *args
args.extend(arg)
else:
# plain argument
args.append(arg)
return tuple(args)
@property
def kwargs(self):
kwargs = {}
kwargs_started = False
for param_name, param in self._signature.parameters.items():
if not kwargs_started:
if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
param._partial_kwarg):
kwargs_started = True
else:
if param_name not in self.arguments:
kwargs_started = True
continue
if not kwargs_started:
continue
try:
arg = self.arguments[param_name]
except KeyError:
pass
else:
if param.kind == _VAR_KEYWORD:
# **kwargs
kwargs.update(arg)
else:
# plain keyword argument
kwargs[param_name] = arg
return kwargs
def __eq__(self, other):
return (issubclass(other.__class__, BoundArguments) and
self.signature == other.signature and
self.arguments == other.arguments)
def __ne__(self, other):
return not self.__eq__(other)
class Signature:
'''A Signature object represents the overall signature of a function.
It stores a Parameter object for each parameter accepted by the
function, as well as information specific to the function itself.
A Signature object has the following public attributes and methods:
* parameters : OrderedDict
An ordered mapping of parameters' names to the corresponding
Parameter objects (keyword-only arguments are in the same order
as listed in `code.co_varnames`).
* return_annotation : object
The annotation for the return type of the function if specified.
If the function has no annotation for its return type, this
attribute is not set.
* bind(*args, **kwargs) -> BoundArguments
Creates a mapping from positional and keyword arguments to
parameters.
* bind_partial(*args, **kwargs) -> BoundArguments
Creates a partial mapping from positional and keyword arguments
to parameters (simulating 'functools.partial' behavior.)
'''
__slots__ = ('_return_annotation', '_parameters')
_parameter_cls = Parameter
_bound_arguments_cls = BoundArguments
empty = _empty
def __init__(self, parameters=None, *, return_annotation=_empty,
__validate_parameters__=True):
'''Constructs Signature from the given list of Parameter
objects and 'return_annotation'. All arguments are optional.
'''
if parameters is None:
params = OrderedDict()
else:
if __validate_parameters__:
params = OrderedDict()
top_kind = _POSITIONAL_ONLY
for idx, param in enumerate(parameters):
kind = param.kind
if kind < top_kind:
msg = 'wrong parameter order: {} before {}'
msg = msg.format(top_kind, param.kind)
raise ValueError(msg)
else:
top_kind = kind
name = param.name
if name is None:
name = str(idx)
param = param.replace(name=name)
if name in params:
msg = 'duplicate parameter name: {!r}'.format(name)
raise ValueError(msg)
params[name] = param
else:
params = OrderedDict(((param.name, param)
for param in parameters))
self._parameters = types.MappingProxyType(params)
self._return_annotation = return_annotation
@classmethod
def from_function(cls, func):
'''Constructs Signature for the given python function'''
if not isinstance(func, types.FunctionType):
raise TypeError('{!r} is not a Python function'.format(func))
Parameter = cls._parameter_cls
# Parameter information.
func_code = func.__code__
pos_count = func_code.co_argcount
arg_names = func_code.co_varnames
positional = tuple(arg_names[:pos_count])
keyword_only_count = func_code.co_kwonlyargcount
keyword_only = arg_names[pos_count:(pos_count + keyword_only_count)]
annotations = func.__annotations__
defaults = func.__defaults__
kwdefaults = func.__kwdefaults__
if defaults:
pos_default_count = len(defaults)
else:
pos_default_count = 0
parameters = []
# Non-keyword-only parameters w/o defaults.
non_default_count = pos_count - pos_default_count
for name in positional[:non_default_count]:
annotation = annotations.get(name, _empty)
parameters.append(Parameter(name, annotation=annotation,
kind=_POSITIONAL_OR_KEYWORD))
# ... w/ defaults.
for offset, name in enumerate(positional[non_default_count:]):
annotation = annotations.get(name, _empty)
parameters.append(Parameter(name, annotation=annotation,
kind=_POSITIONAL_OR_KEYWORD,
default=defaults[offset]))
# *args
if func_code.co_flags & 0x04:
name = arg_names[pos_count + keyword_only_count]
annotation = annotations.get(name, _empty)
parameters.append(Parameter(name, annotation=annotation,
kind=_VAR_POSITIONAL))
# Keyword-only parameters.
for name in keyword_only:
default = _empty
if kwdefaults is not None:
default = kwdefaults.get(name, _empty)
annotation = annotations.get(name, _empty)
parameters.append(Parameter(name, annotation=annotation,
kind=_KEYWORD_ONLY,
default=default))
# **kwargs
if func_code.co_flags & 0x08:
index = pos_count + keyword_only_count
if func_code.co_flags & 0x04:
index += 1
name = arg_names[index]
annotation = annotations.get(name, _empty)
parameters.append(Parameter(name, annotation=annotation,
kind=_VAR_KEYWORD))
return cls(parameters,
return_annotation=annotations.get('return', _empty),
__validate_parameters__=False)
@property
def parameters(self):
return self._parameters
@property
def return_annotation(self):
return self._return_annotation
def replace(self, *, parameters=_void, return_annotation=_void):
'''Creates a customized copy of the Signature.
Pass 'parameters' and/or 'return_annotation' arguments
to override them in the new copy.
'''
if parameters is _void:
parameters = self.parameters.values()
if return_annotation is _void:
return_annotation = self._return_annotation
return type(self)(parameters,
return_annotation=return_annotation)
def __eq__(self, other):
if (not issubclass(type(other), Signature) or
self.return_annotation != other.return_annotation or
len(self.parameters) != len(other.parameters)):
return False
other_positions = {param: idx
for idx, param in enumerate(other.parameters.keys())}
for idx, (param_name, param) in enumerate(self.parameters.items()):
if param.kind == _KEYWORD_ONLY:
try:
other_param = other.parameters[param_name]
except KeyError:
return False
else:
if param != other_param:
return False
else:
try:
other_idx = other_positions[param_name]
except KeyError:
return False
else:
if (idx != other_idx or
param != other.parameters[param_name]):
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
def _bind(self, args, kwargs, *, partial=False):
'''Private method. Don't use directly.'''
arguments = OrderedDict()
parameters = iter(self.parameters.values())
parameters_ex = ()
arg_vals = iter(args)
if partial:
# Support for binding arguments to 'functools.partial' objects.
# See 'functools.partial' case in 'signature()' implementation
# for details.
for param_name, param in self.parameters.items():
if (param._partial_kwarg and param_name not in kwargs):
# Simulating 'functools.partial' behavior
kwargs[param_name] = param.default
while True:
# Let's iterate through the positional arguments and corresponding
# parameters
try:
arg_val = next(arg_vals)
except StopIteration:
# No more positional arguments
try:
param = next(parameters)
except StopIteration:
# No more parameters. That's it. Just need to check that
# we have no `kwargs` after this while loop
break
else:
if param.kind == _VAR_POSITIONAL:
# That's OK, just empty *args. Let's start parsing
# kwargs
break
elif param.name in kwargs:
if param.kind == _POSITIONAL_ONLY:
msg = '{arg!r} parameter is positional only, ' \
'but was passed as a keyword'
msg = msg.format(arg=param.name)
raise TypeError(msg) from None
parameters_ex = (param,)
break
elif (param.kind == _VAR_KEYWORD or
param.default is not _empty):
# That's fine too - we have a default value for this
# parameter. So, lets start parsing `kwargs`, starting
# with the current parameter
parameters_ex = (param,)
break
else:
if partial:
parameters_ex = (param,)
break
else:
msg = '{arg!r} parameter lacking default value'
msg = msg.format(arg=param.name)
raise TypeError(msg) from None
else:
# We have a positional argument to process
try:
param = next(parameters)
except StopIteration:
raise TypeError('too many positional arguments') from None
else:
if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
# Looks like we have no parameter for this positional
# argument
raise TypeError('too many positional arguments')
if param.kind == _VAR_POSITIONAL:
# We have an '*args'-like argument, let's fill it with
# all positional arguments we have left and move on to
# the next phase
values = [arg_val]
values.extend(arg_vals)
arguments[param.name] = tuple(values)
break
if param.name in kwargs:
raise TypeError('multiple values for argument '
'{arg!r}'.format(arg=param.name))
arguments[param.name] = arg_val
# Now, we iterate through the remaining parameters to process
# keyword arguments
kwargs_param = None
for param in itertools.chain(parameters_ex, parameters):
if param.kind == _POSITIONAL_ONLY:
# This should never happen in case of a properly built
# Signature object (but let's have this check here
# to ensure correct behaviour just in case)
raise TypeError('{arg!r} parameter is positional only, '
'but was passed as a keyword'. \
format(arg=param.name))
if param.kind == _VAR_KEYWORD:
# Memorize that we have a '**kwargs'-like parameter
kwargs_param = param
continue
param_name = param.name
try:
arg_val = kwargs.pop(param_name)
except KeyError:
# We have no value for this parameter. It's fine though,
# if it has a default value, or it is an '*args'-like
# parameter, left alone by the processing of positional
# arguments.
if (not partial and param.kind != _VAR_POSITIONAL and
param.default is _empty):
raise TypeError('{arg!r} parameter lacking default value'. \
format(arg=param_name)) from None
else:
arguments[param_name] = arg_val
if kwargs:
if kwargs_param is not None:
# Process our '**kwargs'-like parameter
arguments[kwargs_param.name] = kwargs
else:
raise TypeError('too many keyword arguments')
return self._bound_arguments_cls(self, arguments)
def bind(__bind_self, *args, **kwargs):
'''Get a BoundArguments object, that maps the passed `args`
and `kwargs` to the function's signature. Raises `TypeError`
if the passed arguments can not be bound.
'''
return __bind_self._bind(args, kwargs)
def bind_partial(__bind_self, *args, **kwargs):
'''Get a BoundArguments object, that partially maps the
passed `args` and `kwargs` to the function's signature.
Raises `TypeError` if the passed arguments can not be bound.
'''
return __bind_self._bind(args, kwargs, partial=True)
def __str__(self):
result = []
render_kw_only_separator = True
for idx, param in enumerate(self.parameters.values()):
formatted = str(param)
kind = param.kind
if kind == _VAR_POSITIONAL:
# OK, we have an '*args'-like parameter, so we won't need
# a '*' to separate keyword-only arguments
render_kw_only_separator = False
elif kind == _KEYWORD_ONLY and render_kw_only_separator:
# We have a keyword-only parameter to render and we haven't
# rendered an '*args'-like parameter before, so add a '*'
# separator to the parameters list ("foo(arg1, *, arg2)" case)
result.append('*')
# This condition should be only triggered once, so
# reset the flag
render_kw_only_separator = False
result.append(formatted)
rendered = '({})'.format(', '.join(result))
if self.return_annotation is not _empty:
anno = formatannotation(self.return_annotation)
rendered += ' -> {}'.format(anno)
return rendered