class-based class decorator

Fri Jan 9 16:26:52 EST 2015

Hi,
I am trying to write a class decorator that checks whether deprecated parameters with non-default
arguments are used. More complete code is here: http://pastebin.com/ZqnMis6M. In the code below, 
how should I modify __call__ such that f.bar(old="oh no") prints "hello world"?
I thought it would be a fun way to play with the inspect module, but my head is numb now and I am thirsty for a beer!
import inspectimport functools
import warnings
class check_deprecated_args(object):

 """
 Class decorator that checks whether deprecated parameters with non-default
 arguments are used
 Parameters
 ----------
 deprecated_params : tuple
 tuple of strings of parameters that should raise a DeprecationWarning,
 if they are used with non-default arguments
 Raises
 ------
 DeprecationWarning : if deprecated parameters are used with 
 non-default arguments in the class's constructor.
 """
 def __init__(self, deprecated_params):
 self.deprecated_params = deprecated_params
 def __call__(self, cls):
 @functools.wraps(cls)
 def inner(*used_args, **used_kwargs):
 print "called" 
 # insert sneaky 'inspect' code here
 #pprint( dict(inspect.getmembers(cls)) )
 return cls # --- this is wrong, it should return the Foo instance object!
 return inner
if __name__ == "__main__":
 @check_deprecated_args(deprecated_params=("old", "older"))
 class Foo(object):
 def __init__(self, old=True, older=None, new="yaay"):
 pass
 def bar(self, old=True, new=True):
 print "hello world"
 f = Foo(new="great", old="obsolete", older="stop using it")
 print repr(f)
 print f.bar(old="oh no")

Regards,
Albert-Jan
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