forked from varia/varia.website
93 lines
2.4 KiB
Python
93 lines
2.4 KiB
Python
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import inspect
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import six
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# Modifies class methods (or instances of them) on the fly
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# http://blog.ianbicking.org/2007/08/08/opening-python-classes/
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# http://svn.colorstudy.com/home/ianb/recipes/magicset.py
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# including python 3 fixes for func_name => __name__ and types.ClassType => type
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def magic_set(obj):
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"""
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Adds a function/method to an object. Uses the name of the first
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argument as a hint about whether it is a method (``self``), class
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method (``cls`` or ``klass``), or static method (anything else).
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Works on both instances and classes.
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>>> class color:
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... def __init__(self, r, g, b):
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... self.r, self.g, self.b = r, g, b
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>>> c = color(0, 1, 0)
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>>> c # doctest: +ELLIPSIS
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<__main__.color instance at ...>
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>>> @magic_set(color)
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... def __repr__(self):
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... return '<color %s %s %s>' % (self.r, self.g, self.b)
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>>> c
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<color 0 1 0>
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>>> @magic_set(color)
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... def red(cls):
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... return cls(1, 0, 0)
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>>> color.red()
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<color 1 0 0>
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>>> c.red()
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<color 1 0 0>
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>>> @magic_set(color)
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... def name():
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... return 'color'
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>>> color.name()
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'color'
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>>> @magic_set(c)
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... def name(self):
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... return 'red'
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>>> c.name()
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'red'
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>>> @magic_set(c)
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... def name(cls):
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... return cls.__name__
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>>> c.name()
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'color'
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>>> @magic_set(c)
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... def pr(obj):
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... print obj
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>>> c.pr(1)
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1
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"""
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def decorator(func):
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is_class = isinstance(obj, six.class_types)
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args, varargs, varkw, defaults = inspect.getargspec(func)
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if not args or args[0] not in ('self', 'cls', 'klass'):
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# Static function/method
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if is_class:
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replacement = staticmethod(func)
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else:
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replacement = func
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elif args[0] == 'self':
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if is_class:
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replacement = func
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else:
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def replacement(*args, **kw):
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return func(obj, *args, **kw)
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try:
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replacement.__name__ = func.__name__
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except:
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pass
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else:
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if is_class:
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replacement = classmethod(func)
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else:
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def replacement(*args, **kw):
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return func(obj.__class__, *args, **kw)
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try:
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replacement.__name__ = func.__name__
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except:
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pass
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setattr(obj, func.__name__, replacement)
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return replacement
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return decorator
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if __name__ == '__main__':
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import doctest
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doctest.testmod()
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