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    <p>All we really need to do is modify the behavior of the decorator so that it is "hygienic", i.e. it is attribute-preserving.</p> <pre><code>#!/usr/bin/python3 def hygienic(decorator): def new_decorator(original): wrapped = decorator(original) wrapped.__name__ = original.__name__ wrapped.__doc__ = original.__doc__ wrapped.__module__ = original.__module__ return wrapped return new_decorator </code></pre> <p>This is ALL you need. In general. It doesn't preserve the signature, but if you really want that you can use a library to do that. I also went ahead and rewrote the memoization code so that it works on keyword arguments as well. Also there was a bug where failure to convert it to a hashable tuple would make it not work in 100% of cases.</p> <p>Demo of rewritten <code>memoized</code> decorator with <code>@hygienic</code> modifying its behavior. <code>memoized</code> is now a function that wraps the original class, though you can (like the other answer) write a wrapping class instead, or even better, something which detects if it's a class and if so wraps the <code>__init__</code> method.</p> <pre><code>@hygienic class memoized: def __init__(self, func): self.func = func self.cache = {} def __call__(self, *args, **kw): try: key = (tuple(args), frozenset(kw.items())) if not key in self.cache: self.cache[key] = self.func(*args,**kw) return self.cache[key] except TypeError: # uncacheable -- for instance, passing a list as an argument. # Better to not cache than to blow up entirely. return self.func(*args,**kw) </code></pre> <p>In action:</p> <pre><code>@memoized def f(a, b=5, *args, keyword=10): """Intact docstring!""" print('f was called!') return {'a':a, 'b':b, 'args':args, 'keyword':10} x=f(0) #OUTPUT: f was called! print(x) #OUTPUT: {'a': 0, 'b': 5, 'keyword': 10, 'args': ()} y=f(0) #NO OUTPUT - MEANS MEMOIZATION IS WORKING print(y) #OUTPUT: {'a': 0, 'b': 5, 'keyword': 10, 'args': ()} print(f.__name__) #OUTPUT: 'f' print(f.__doc__) #OUTPUT: 'Intact docstring!' </code></pre>
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    1. POPython functools.wraps equivalent for classes
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    1. COThis isn't working for the memoized example.
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    2. CO@Neil: there we go, updated
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    3. COThe @hygienic does not work for code where the wrapped decorator class has a class attribute. Mouad's solution works though. The problem reported is: `AttributeError: 'function' object has no attribute 'level'` when trying to do `decoratorclassname.level += 1` inside the `__call__`
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