[IronPython] staticmethod / classmethod and setattr

[Michael Foord]

 From http://www.ddj.com/web-development/184406073

Usually, most decorators expect a function on input, and return either a 
function or an attribute descriptor as their output. The Python 
built-ins classmethod, staticmethod, and property all return attribute 
descriptors, so their output cannot be passed to a decorator that 
expects a function. That's why I had to put classmethod first in Listing 
Four. As an experiment, try reversing the order of @traced and 
@classmethod in Listing Four, and see if you can guess what will happen.


Curt Hagenlocher wrote:
> This is really more of a Python question than an IronPython question, 
> but I'm not currently on any non-Iron Python lists. :)
>  
> The following definition results in an error under both CPython 2.5 
> and IronPython.  Decorating a method as static or class prevents 
> attributes being set on the resulting definition.
>  
> def decorate(obj):
>     obj.decorated = True
>     return obj
>  
> class X:
>     @decorate
>     @staticmethod
>     def foo():
>         pass
>  
> Does anyone know the "why" of this behavior? 
>  
> I can work around this problem by declaring the decorators in the 
> opposite order, but it seems like an odd imposition to put on the 
> consumers of the code in question.  I'm worried that I'm missing 
> something about the expected semantics of these standard functions.
>  
> --
> Curt Hagenlocher
> curt at hagenlocher.org <mailto:curt at hagenlocher.org>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Users mailing list
> Users at lists.ironpython.com
> http://lists.ironpython.com/listinfo.cgi/users-ironpython.com
>