py3k feature proposal: field auto-assignment in constructors

[Steven Bethard]

Arnaud Delobelle wrote:
> Sligthly improved (not for performance! but signature-preserving and
> looks for default values)
> 
> from functools import wraps
> from inspect import getargspec
> from itertools import izip, chain
> 
> def autoassign(*names):
>     def decorator(f):
>         fargnames, _, _, fdefaults = getargspec(f)
>         defaults = [(n,v) for (n,v)
>                     in izip(reversed(fargnames), reversed(fdefaults))
>                     if n in names]
>         @wraps(f)
>         def decorated(self, *args, **kwargs):
>             self.__dict__.update(defaults)
>             for name, arg in chain(izip(fargnames, args),
>                                    kwargs.iteritems()):
>                 if name in names:
>                     setattr(self, name, arg)
>             return f(self, *args, **kwargs)
>         return decorated
>     return decorator
> 
> class Test(object):
>      @autoassign('foo', 'bar')
>      def __init__(self, foo, bar=3, baz=6):
>          print 'baz =', baz
> 
> t = Test(1, 2, 6)
> u = Test(foo=8)
> 
> print t.foo # 1
> print t.bar # 2
> 
> print u.foo # 8
> print u.bar # 3 (default)

You should definitely post this to the cookbook:

     http://aspn.activestate.com/ASPN/Cookbook/Python

STeVe