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