[Python-Dev] Re: PEP 318: Decorators last before colon (original) (raw)

Andrew Koenig ark-mlist at att.net
Mon Apr 5 10:42:40 EDT 2004

[I've mentioned this idea before, but don't recall seeing any responses to it; so I'm mentioning it again in case it got lost the first time]

I am concerned about putting decorators before the function definition because of the possibility of such code quietly sneaking through existing compilers:

[classmethod]
def foo(bar, baz):
    pass

Guido is concerned about putting decorators after the function definition because there may be a lot of them and it may be hard to read:

def foo(bar, baz) \
    [staticmethod, classmethod, otherattributes(debug=True}) }:
    pass

Here's what I don't understand.

I imagine that most of the time, when someone decorates a function with lots of attributes, there is at least the possibility of decorating more than one function with the same set of attributes.

In such a case, doesn't it make sense to bind a variable to the attributes and use it instead?

Attributes = [staticmethod, classmethod,

otherattributes(debug=True)]

def foo(bar, baz) Attributes:
    pass

And doesn't this idea answer the objection that too many attributes after the parameter list make the definition hard to read?

For that matter, why do we need the brackets if there is only one attribute:

def foo(bar, baz) staticmethod:
    pass

I am suggesting that what comes between the ) and the : should be an expression, which must evaluate to either a callable or a sequence of callables. For that matter, why not allow a tuple expression without parentheses:

def foo(bar, baz) staticmethod, classmethod:
    pass

Whatever sequence you put there, I think the semantics are clear: Before binding a name to the function, pass it to the callable or in turn to each element of the sequence.

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