Registry of Methods via Decorators

[Maric Michaud]

Hi,

Le Jeudi 22 Juin 2006 15:32, bayerj a écrit :
> I want to make a registry of methods of a class during creation.
Why ? you already have them in dec2.__dict__ :

In [42]: import types

In [43]: class a :
   ....:     def b(self) : return
   ....:     @classmethod
   ....:     def c(self) : return
   ....:
   ....:

In [44]: [ k for k, v in a.__dict__.items() if isinstance(v, 
types.FunctionType) ]
Out[44]: ['b']

In [45]: [ k for k, v in a.__dict__.items() if isinstance(v, classmethod) ]
Out[45]: ['c']

Warning :

In [46]: list(isinstance(i, types.MethodType) for i in (a.b, a().b, 
a.__dict__['b']))
Out[46]: [True, True, False]

In [47]: list(isinstance(i, types.FunctionType) for i in (a.b, a().b, 
a.__dict__['b']))
Out[47]: [False, False, True]

I would prefer write some inspection method that retrieve all these infos.

> My 
> attempt was this

And that can't work,

>
> """ classdecorators.py
>
> Author: Justin Bayer
> Creation Date: 2006-06-22
> Copyright (c) 2006 Chess Pattern Soft,
> All rights reserved.  """
>
> class decorated(object):
>
>     methods = []
>
>     @classmethod
>     def collect_methods(cls, method):
>         cls.methods.append(method.__name__)
>         return method
>
> class dec2(decorated):
>
>     @collect_methods
>     def first_func(self):
>         pass
>
>     @collect_methods
>     def second_func(self):
>         pass
>
This is trying to do :
    first_func = collect_methods(first_fun)
but collect_methods doesn't exists in the global namespace (indeed you got a 
NameError exception).

You can't reference it as decorated.collect_methods because the methods will 
be appended to the decorated.methods list and not one list specific to dec2. 
You neither can refer it as dec2.collect_methods because dec2 is still 
undefined.

>
> def main():
>     print dec2.methods
>
> if __name__ == '__main__':
>     main()
>
> This does not work and exits with "NameError: ("name 'collect_methods'
> is not defined",)". Which is understandable due to the fact that the
> class dec2 is not complete.
Not exactly.
At any moment in a python program, there are two and only two scope, global 
and local, global is usually the module level scope (where 
no 'collect_methods' exists), and, in the case of a class definition, local 
is the class __dict__ (the local namespace is not same the class and its 
method).


But I'm not sure of what you really want : a list of all decorated methods of 
all subclasses of a class, or a list of marked method in each class ?

-- 
_____________

Maric Michaud
_____________

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