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Viewing changes to Demo/metaclasses/Simple.py

  • Committer: Bazaar Package Importer
  • Author(s): Matthias Klose
  • Date: 2009-03-23 00:01:27 UTC
  • Revision ID: james.westby@ubuntu.com-20090323000127-5fstfxju4ufrhthq
Tags: upstream-3.1~a1+20090322
Import upstream version 3.1~a1+20090322

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Demo/metaclasses/Simple.py
 
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import types
 
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class Tracing:
 
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    def __init__(self, name, bases, namespace):
 
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        """Create a new class."""
 
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        self.__name__ = name
 
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        self.__bases__ = bases
 
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        self.__namespace__ = namespace
 
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    def __call__(self):
 
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        """Create a new instance."""
 
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        return Instance(self)
 
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class Instance:
 
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    def __init__(self, klass):
 
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        self.__klass__ = klass
 
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    def __getattr__(self, name):
 
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        try:
 
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            value = self.__klass__.__namespace__[name]
 
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        except KeyError:
 
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            raise AttributeError(name)
 
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        if type(value) is not types.FunctionType:
 
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            return value
 
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        return BoundMethod(value, self)
 
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class BoundMethod:
 
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    def __init__(self, function, instance):
 
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        self.function = function
 
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        self.instance = instance
 
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    def __call__(self, *args):
 
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        print("calling", self.function, "for", self.instance, "with", args)
 
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        return self.function(self.instance, *args)
 
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Trace = Tracing('Trace', (), {})
 
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class MyTracedClass(Trace):
 
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    def method1(self, a):
 
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        self.a = a
 
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    def method2(self):
 
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        return self.a
 
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aninstance = MyTracedClass()
 
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aninstance.method1(10)
 
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print(aninstance.method2())