Turning a signature-changing decorator into a signature-preserving one

Michele Simionato michele.simionato at gmail.com
Mon Feb 16 11:18:00 EST 2009

On Feb 16, 4:59 pm, Gustavo Narea <m... at gustavonarea.net> wrote:
> I've not seen anything special in Pylons or TurboGears 2 decorators,
> except that they are all functions that use the decorator package --
> while my decorator is a class that doesn't use the decorator package
> yet.
> My attempt to turn that decorator into a signature preserving one
> using the decorator packages fails even on TurboGears 2. As of
> decorator 3.0.1, I get this error:
>     TypeError: You are decorating a non function: <unbound method
> SecurePanel.__before__>
> Isn't this caused by the fact that my decorator is a class, or the way
> such a class is defined (whose code is in the first post of the
> thread)? I can turn it into a function because I'm sure I'll work --
> although I wanted a class to make it easier to customize.
> Thanks.

The decorator class is fine, the error in clearly in what you pass to
the decorator.
You are trying to decorate an unbound method SecurePanel.__before__:
are you
sure this is really what you want to decorate? Are you decorating
automatically all methods
of SecurePanel? I have already mentioned it, but you can extract the
underlying function
from the method by using  SecurePanel.__before__.im_func if you really

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