[Twisted-web] Returning Deferred from coerce method in formless - patch

[Michal Pasternak]

Hi,

	http://divmod.org/users/roundup.twistd/nevow/msg436
	
Coerce methods, used when validating formless.annotate.Typed
objects, can return Deferreds. The problem with formless is,
that it can accept them only when GroupBinding is used. This
patch fixes that for MethodBinding.

Why return Deferred from coerce methods? Well, there are
various reasons. You could validate an e-mail address using
queries to DNS servers, or you could validate login name
using pgasync.ConnectionPool, or do anything else, that
requires deferred methods.

Even that I've still have Nevow commits, I don't want to
commit this patch myself - I'd really appreciate someone
reviewing it before.

Many thanks,
-- 
m