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Possible PEP: Improve classmethod/staticmethod syntax

sismex01 at hebmex.com sismex01 at hebmex.com
Wed Jun 4 13:34:52 EDT 2003 
> From: Lulu of the Lotus-Eaters [mailto:mertz at gnosis.cx]
> Sent: Wednesday, June 04, 2003 11:55 AM
> 
> Duncan Booth <duncan at NOSPAMrcp.co.uk> wrote previously:
> |>     def fooDoc(f):
> |>         f.__doc__ = "Bob's your uncle."
> |>         return f
> |>     class Klass(object):
> |>         def meth(this, that) [fooDoc]:
> |>             pass
> |Or better:
> |
> |def Doc(docstring, **kw):
> |    def fDoc(f):
> |        f.__doc__ = docstring
> |        f.__dict__.update(kw)
> |        return f
> |class Klass(object):
> |    def meth(this, that) [Doc("Bob's your uncle.", Author="me")]:
> |        pass
> 
> I don't understand this version.  I see the idea that you want to pass
> arguments to the "function constructor"--but where does the name 'fDoc'
> come from?  How does 'Doc()' know to call 'fDoc()' (which I presume it
> wants to)?
> 
> Yours, Lulu...
>

It doesn't... I mean, Doc() doesn't call fDoc().  Doc() is a factory
function which produces functions which in turn are used to apply
transformations upon other functions.

So, in the declaration:

   def meth(this,that) [Doc("Bob's your uncle.", Author="me")]:
           pass

So, Doc(...) produces a function (fDoc) which applies decorations
to any function passed to it.  It'd be equivalent to:

   UncleBobFunc = Doc("Bob's your uncle.", Author="me")

   def meth(this,that) [UncleBobFunc]:
           pass

And, the transformation-application-mechanism inside the compiler,
internally, does something like:

   for transform in [UncleBobFunc]:
      meth = transform(meth)

for every transformation in the list.  That's why I like the list-like
notation best, it's very simple to implement in the compiler
machinery, very easy on the eyes, and simple to parse visually.

HTH!

-gca
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