[Python-Dev] Definining properties - a use case for class decorators? (original) (raw)

Michael Urman murman at gmail.com
Mon Oct 17 09:09:12 CEST 2005

On 10/16/05, Nick Coghlan <ncoghlan at iinet.net.au> wrote:

On and off, I've been looking for an elegant way to handle properties using decorators.

Why use decorators when a metaclass will already do the trick, and save you a line? This doesn't necessarily get around Antoine's complaint that it looks like self refers to the wrong type, but I'm not convinced anyone would be confused.

class MetaProperty(type): def new(cls, name, bases, dct): if bases[0] is object: # allow us to create class Property return type.new(cls, name, bases, dct) return property(dct.get('get'), dct.get('set'), dct.get('delete'), dct.get('doc'))

def __init__(cls, name, bases, dct):
    if bases[0] is object:
        return type.__init__(cls, name, bases, dct)

class Property(object): metaclass = MetaProperty

class Test(object): class foo(Property): """The foo property""" def get(self): return self._foo def set(self, val): self._foo = val def delete(self): del self._foo

test = Test() test.foo = 'Yay!' assert test._foo == 'Yay!'

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