On Aug 19, 2004, at 3:30 PM, Paul Morrow wrote:
> James Y Knight wrote:
>
>> On Aug 19, 2004, at 7:45 AM, Paul Morrow wrote:
>>> The vast majority of instance methods I've seen all use 'self' as
>>> the first parameter. Likewise, most class methods use 'cls' or
>>> 'klass' as their first parameter. If we exploit these conventions,
>>> we end up with a simple, clear, obvious mechanism for denoting (this
>>> aspect of) a method's type.
>>>
>>> class Foo(Object):
>>> def m1(self, a, b): # this is an instance method of Foo
>>> pass
>>>
>>> def m2(cls, a, b): # this is a class method of Foo
>>> pass
>>>
>>> def m3(a, b): # this is a static method of Foo
>>> pass
>>>
>>> A special Object (capital 'O') class could work this magic so that
>>> old code didn't break.
>>>
>>> I know that this is odd. But then so are most of the great things
>>> about Python.
>> You can do that today. See also
>> http://www.python.org/pycon/dc2004/papers/48/conveniencytypes.py
>
> Aha! Thanks!
Whatever happened to explicit is better than implicit? ;)
>> However, note that IMO it is quite rude to use a metaclass (or your
>> capital O object -- same thing) to do this, as it will break any
>> objects inheriting from your class that don't expect the strange
>> automatic behavior. This auto-class/staticmethod-ification should be
>> local to your code, and thus is really a candidate for a class
>> decorator.
>> @automethods
>> class Foo(object):
>> ...
>
> But then wouldn't subclasses of Foo have the same rude behavior? In
> fact, isn't the use of any metaclass rude, by your definition, as it
> will change the default class behavior in some way?
No, a decorator happens once. A metaclass can/does have permanent
effects and becomes an integral and/or annoying part of the inheritance
graph.
class Foo(object):
__metaclass__ = Bar
...
is *much* different than
class Foo(object):
...
Foo = barEquivalentFunction(Foo)
which is the same as
@barEquivalentFunction
class Foo(object):
...
-bob
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