[Python-Dev] Re: PEP 318: Can't we all just get along? (original) (raw)

Paul Morrow pm_mon at yahoo.com
Thu Aug 19 13:45:09 CEST 2004

Jim Fulton wrote:

IMO, yes, although I'd happily accept both syntaxes. I can live with @foo to server the people who want it, but it bugs me that I have to write: @clasmethod def foo .... rather than the, to me, much more obvious and readable: def classmethod foo ...

Probably the best-loved features of Python are the shortcuts. The fact that you don't have to explicitly declare very much and that the language supports clear, shorthand syntax for frequently used operations...

x = [1,2,3]

y = r[2:9]

def __foo():

That's the good stuff of Python.

I believe that identifying staticmethods and classmethods is an operation that is (or will be) frequently used as compared to the other decorators. So it would be great if there was an obvious, shorthand way for doing that as well.

Even better (IMO) would be a solution that didn't really add any new keywords to the language, but instead simply formalized widely-used coding conventions, as was done to denote code block boundaries.

The use of indentation to identify code blocks is a wonderful example of Python shorthand. It works (some even call it 'genius') because it leverages a coding convention shared by a majority of programmers.

A week or so ago, Stefan Eischet on comp.lang.python suggested that the type (static|class|instance) of a method could be inferred through examination of its first parameter. I agree with his assessment.

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.

Paul

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