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- '''
- This module provides a newsuper() function in Python 2 that mimics the
- behaviour of super() in Python 3. It is designed to be used as follows:
- from __future__ import division, absolute_import, print_function
- from future.builtins import super
- And then, for example:
- class VerboseList(list):
- def append(self, item):
- print('Adding an item')
- super().append(item) # new simpler super() function
- Importing this module on Python 3 has no effect.
- This is based on (i.e. almost identical to) Ryan Kelly's magicsuper
- module here:
- https://github.com/rfk/magicsuper.git
- Excerpts from Ryan's docstring:
- "Of course, you can still explicitly pass in the arguments if you want
- to do something strange. Sometimes you really do want that, e.g. to
- skip over some classes in the method resolution order.
- "How does it work? By inspecting the calling frame to determine the
- function object being executed and the object on which it's being
- called, and then walking the object's __mro__ chain to find out where
- that function was defined. Yuck, but it seems to work..."
- '''
- from __future__ import absolute_import
- import sys
- from types import FunctionType
- from future.utils import PY3, PY26
- _builtin_super = super
- _SENTINEL = object()
- def newsuper(typ=_SENTINEL, type_or_obj=_SENTINEL, framedepth=1):
- '''Like builtin super(), but capable of magic.
- This acts just like the builtin super() function, but if called
- without any arguments it attempts to infer them at runtime.
- '''
- # Infer the correct call if used without arguments.
- if typ is _SENTINEL:
- # We'll need to do some frame hacking.
- f = sys._getframe(framedepth)
- try:
- # Get the function's first positional argument.
- type_or_obj = f.f_locals[f.f_code.co_varnames[0]]
- except (IndexError, KeyError,):
- raise RuntimeError('super() used in a function with no args')
- try:
- # Get the MRO so we can crawl it.
- mro = type_or_obj.__mro__
- except (AttributeError, RuntimeError): # see issue #160
- try:
- mro = type_or_obj.__class__.__mro__
- except AttributeError:
- raise RuntimeError('super() used with a non-newstyle class')
- # A ``for...else`` block? Yes! It's odd, but useful.
- # If unfamiliar with for...else, see:
- #
- # http://psung.blogspot.com/2007/12/for-else-in-python.html
- for typ in mro:
- # Find the class that owns the currently-executing method.
- for meth in typ.__dict__.values():
- # Drill down through any wrappers to the underlying func.
- # This handles e.g. classmethod() and staticmethod().
- try:
- while not isinstance(meth,FunctionType):
- if isinstance(meth, property):
- # Calling __get__ on the property will invoke
- # user code which might throw exceptions or have
- # side effects
- meth = meth.fget
- else:
- try:
- meth = meth.__func__
- except AttributeError:
- meth = meth.__get__(type_or_obj, typ)
- except (AttributeError, TypeError):
- continue
- if meth.func_code is f.f_code:
- break # Aha! Found you.
- else:
- continue # Not found! Move onto the next class in MRO.
- break # Found! Break out of the search loop.
- else:
- raise RuntimeError('super() called outside a method')
- # Dispatch to builtin super().
- if type_or_obj is not _SENTINEL:
- return _builtin_super(typ, type_or_obj)
- return _builtin_super(typ)
- def superm(*args, **kwds):
- f = sys._getframe(1)
- nm = f.f_code.co_name
- return getattr(newsuper(framedepth=2),nm)(*args, **kwds)
- __all__ = ['newsuper']
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