[Python-Dev] method decorators (PEP 318) (original) (raw)

Bernhard Herzog bh at intevation.de
Sat Mar 27 12:39:25 EST 2004

"Jewett, Jim J" <jim.jewett at eds.com> writes:

Guido van Rossum:

... for decorators spelled with a single word, like classmethod, ... as early as reasonable in the function definition def foobar(cls, blooh, blah) [classmethod]: hides a more important fact for understanding it (classmethod) behind some less important facts (the argument list). I would much rather see this: def foobar [classmethod] (cls, blooh, blah): One alternative placed it earlier still, in a second header clause. using: classmethod def foobar(cls, blooh, blah): pass

Has somebody suggested the following yet?

def [classmethod] foo(cls, blooh, bla):
    pass

or for a longer list of decorators

def [classmethod, 
     attributes(deprecated=True)
    ] foo(cls, blooh, bla):
    pass

It might be more readable if a newline were allowed between the closing ] and the function name:

def [classmethod, attributes(deprecated=True)]
    foo(cls, blooh, bla):
    pass

Putting the decorators between the "def" and the function name has some advantages over the proposals I've seen so far:

- crucial information about the function and the meaning of the
  parameters is given very early (this was an argument made for
  putting the decorat before the argument list)

- The name and the argument are together, so it still looks similar
  to the function invocation (an argument made for putting the
  decorators after the function list).

If the decorators come before the function name, the decorators should perhaps be applied in reverse order so that

def [classmethod, deprecated] foo(cls, bar): pass

is similar to

def foo(cls, bar): pass foo = classmethod(deprecated(foo))

Bernhard

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