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55 lines
2.0 KiB
55 lines
2.0 KiB
"""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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import sys
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if sys.hexversion >= 0x3000000:
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im_func = '__func__'
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im_self = '__self__'
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im_code = '__code__'
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func_code = '__code__'
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else:
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im_func = 'im_func'
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im_self = 'im_self'
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im_code = 'im_code'
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func_code = 'func_code'
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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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# 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, getattr(getattr(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, getattr(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 name in named:
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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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named = dict([(k,v) for k,v in named.items() if k in acceptable])
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return receiver(*arguments, **named)
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