Viewing file:  robustapply.py (2.1 KB) -rw-r--r--
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"""Robust apply mechanism.
Provides a function 'call', which can sort out what arguments a given
callable object can take, and subset the given arguments to match only
those which are acceptable.
"""
def function(receiver):
"""Get function-like callable object for given receiver.
returns (function_or_method, codeObject, fromMethod)
If fromMethod is true, then the callable already has its first
argument bound.
"""
if hasattr(receiver, '__call__'):
# receiver is a class instance; assume it is callable.
# Reassign receiver to the actual method that will be called.
c = receiver.__call__
if hasattr(c, 'im_func') or hasattr(c, 'im_code'):
receiver = c
if hasattr(receiver, 'im_func'):
# receiver is an instance-method.
return receiver, receiver.im_func.func_code, 1
elif not hasattr(receiver, 'func_code'):
raise ValueError(
'unknown reciever type %s %s' % (receiver, type(receiver)))
return receiver, receiver.func_code, 0
def robust_apply(receiver, signature, *arguments, **named):
"""Call receiver with arguments and appropriate subset of named.
``signature`` is the callable used to determine the call signature
of the receiver, in case ``receiver`` is a callable wrapper of the
actual receiver."""
signature, code_object, startIndex = function(signature)
acceptable = code_object.co_varnames[
startIndex + len(arguments):
code_object.co_argcount
]
for name in code_object.co_varnames[
startIndex:startIndex + len(arguments)
]:
if named.has_key(name):
raise TypeError(
'Argument %r specified both positionally '
'and as a keyword for calling %r'
% (name, signature)
)
if not (code_object.co_flags & 8):
# fc does not have a **kwds type parameter, therefore
# remove unacceptable arguments.
for arg in named.keys():
if arg not in acceptable:
del named[arg]
return receiver(*arguments, **named)
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