[Python-Dev] PEP 318

[Jewett, Jim J]

PEP-318 (Skip):

>>     def func [dec1, dec2, ...] (arg1, arg2, ...):
>>         pass

>> ... For short lists it works okay, but for long list it separates
>> the argument list from the function name.

Guido van Rossum:

> OTOH, for long argument lists, the "preferred" form has the reverse
> problem: the decorators are separated from the function name by the
> long argument list.

I know it is common to look for "what would I call this with".  
I suppose staticmethod and classmethod are important because they 
change that calling signature.

Are other decorators expected to be something people would scan for?  
If not, then having them at the top of the function (so you see them 
if you're reading the whole function) is probably enough.

> ... what is more likely: long argument lists or long lists of 
> decorators?  I *know* that (at least in certain code bases :)
> long argument lists are common. 

I suspect those same code bases will pass long argument lists to 
several of the individual decorators.  Anders Munch's original 
release example used more than two keywords.  I believe the following 
example is just as reasonable as a long argument list.

Before the def, using an optional second header clause on the 
funcdef production:

    using:
        release(version="1.0",
                author="me",
                status="Well I wrote it so it works, m'kay?",
                warning="You might want to use the Foo class instead")
        provides_API_myweb
        synchronized(lock[23])
    def foo(arg1, arg2):
        pass

In the middle:

    def foo as [release(version="1.0",
                        author="me",
                        status="Well I wrote it so it works, m'kay?",
                  # Line length becomes an issue
                  warning="You might want to use the Foo class instead"),
                provides_API_myweb,
                synchronized(lock[23])] (arg1, arg2):
        pass

At the end:

    def foo(arg1, arg2) as [release(version="1.0",
                                    author="me",
                  # Line length becomes an issue
                  status="Well I wrote it so it works, m'kay?",
                  warning="You might want to use the Foo class instead"),
                            provides_API_myweb,
                            synchronized(lock[23])]:
        pass