[Python-Dev] Decorator order implemented backwards?

James Y Knight foom at fuhm.net
Tue Aug 10 05:16:39 CEST 2004

I haven't seen anyone remark upon this yet, but the order of decorator 
application appears to be implemented backwards.

According to the PEP:
> Proposed Syntax
> The current syntax for function decorators as implemented in Python 
> 2.4a2 is:
> @dec2
> @dec1
> def func(arg1, arg2, ...):
>     pass
> This is equivalent to:
> def func(arg1, arg2, ...):
>     pass
> func = dec2(dec1(func))

However, it seems the '@' form is really doing dec1(dec2(func)), not 
The test_decorators.py reveals that it is, indeed, testing *for* the 
wrong behavior.

>     def test_order(self):
>         class C(object):
>             @funcattrs(abc=1) @staticmethod
>             def foo(): return 42
>         # This wouldn't work if staticmethod was called first
>         self.assertEqual(C.foo(), 42)
>         self.assertEqual(C().foo(), 42)

So, um...I assume this is a bug in the implementation, not the PEP, 
because the PEP's way makes sense and the way it's implemented doesn't.


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