[Python-Dev] method decorators (PEP 318)

[Bob Ippolito]

On Mar 26, 2004, at 11:08 AM, Jack Diederich wrote:

> On Fri, Mar 26, 2004 at 07:10:34AM -0800, Guido van Rossum wrote:
>> We came to an interesting conclusion (which Robert had anticipated):
>> there are two quite different groups of use cases.
>>
>> The other group of use cases merely attaches extra bits of metadata to
>> the method, without changing its usage.  That is what most C# and Java
>> decorators are used for.
> I've posted some examples in the 318 threads of both kinds,
> the function decorators I use tend to change behavior and
> the class decorators I use tend to be meta-markup.
>
> For class decorators I currently use a work around w/ metaclasses,
> I don't decorate functions much so I just do it the old fashioned way.
>
>> So, anyway, here's a new suggestion (inspired by Robert's proposal):
>> (2) Invent some other notation for setting function attributes as part
>>     of the function *body*, before the doc string even.
>>
>> For (2) I am thinking aloud here:
>>
>>    def foobar(self, arg):
>>        @author: "Guido van Rossum"
>>        @deprecated
>>        pass
>
> I'm agnostic on '@' but this looks like pydoc markup to me, what about
>
> def foobar(self, arg):
>   @author = "Guido van Rossum"
>   @deprecated = True
>
> People will also want to access these, so also consider how this will 
> read:
>
> def foobar(self, arg):
>   @author = "Guido"
>   @email = @author.lower() + '@python.org' # contrived example
>
> I'd be a little worried that new users from other languages would start
> using '@' as a synonym for 'this' in strange ways.  Nothing that can't
> be remedied with a clue bat.

Would we call that Rython or Puby?

FWIW, I agree with PJE.  I want one syntax to rule them all, I see no 
need to use two, even though there are different use cases.  Clearly we 
use foo[bar] syntax for different things depending on what foo is, and 
I haven't seen any complaints about that.

-bob