Nick Coghlan <[EMAIL PROTECTED]> wrote:
>
> Reinhold Birkenfeld wrote:
> > Michele Simionato wrote:
> >> As other explained, the syntax would not work for functions (and it is
> >> not intended to).
> >> A possible use case I had in mind is to define inlined modules to be
> >> used as bunches
> >> of attributes. For instance, I could define a module as
> >>
> >> module m():
> >> a = 1
> >> b = 2
> >>
> >> where 'module' would be the following function:
> >>
> >> def module(name, args, dic):
> >> mod = types.ModuleType(name, dic.get('__doc__'))
> >> for k in dic: setattr(mod, k, dic[k])
> >> return mod
> >
> > Wow. This looks like an almighty tool. We can have modules, interfaces,
> > classes and properties all the like with this.
> >
> > Guess a PEP would be nice.
>
> Very nice indeed. I'd be more supportive if it was defined as a new statement
> such as "create" with the syntax:
>
> create TYPE NAME(ARGS):
> BLOCK
>
> The result would be roughly equivalent to:
>
> kwds = {}
> exec BLOCK in kwds
> NAME = TYPE(NAME, ARGS, kwds)
And is equivalent to the class/metaclass abuse...
#suport code
def BlockMetaclassFactory(constructor):
class BlockMetaclass(type):
def __new__(cls, name, bases, dct):
return constructor(name, bases, dct)
return BlockMetaClass
#non-syntax syntax
class NAME(ARGS):
__metaclass__ = BlockMetaclassFactory(TYPE)
BLOCK
Or even...
def BlockClassFactory(constructor):
class BlockClass:
__metaclass__ = BlockMetaclassFactory(constructor)
return BlockClass
class NAME(BlockClassFactory(TYPE), ARGS):
BLOCK
To be used with properties, one could use a wrapper and class definition...
def _Property(names, bases, dct):
return property(**dct)
Property = BlockClassFactory(_Property)
class foo(object):
class x(Property):
...
With minor work, it would be easy to define a subclassable Property
which could handle some basic styles: write once, default value, etc.
I am unconvinced that a block syntax is necessary or desireable for this
case. With the proper support classes, you can get modules, classes,
metaclasses, properties, the previous 'given:' syntax, etc.
- Josiah
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