From: Marco (mrcekets_at_[hidden])
Date: 2007-10-12 13:16:07
On Fri, 12 Oct 2007 08:56:50 +0200, Marco Costalba <mcostalba_at_[hidden]>
> On 10/12/07, Marco Costalba <mcostalba_at_[hidden]> wrote:
>> So I would say a _possible_ policy is to not allow to register say
>> if is already registered a function with a "compatible" signature.
> This is wrong.
> I would have said:
> " a _possible_ policy is that a call like
> overwrites any exsisting function with the same signature *or with a
> compatible signature*"
Not sure to have understood your question.
Anyway this is the assignment policy followed by the latest version
of my implementation:
Let be "ov" an instantiation of the overload template class for
a given set of signatures "ss" used as template arguments:
- if the passed functor "f" is a free function or a member function
- if "f" is not overloaded and its signature is included in "ss"
then the new target (i.e. "f") overwrites the target related
to the matching signature;
- if the signature of "f" is not included in "ss" a compile time
error is produced;
- if "f" is overloaded an "unresolved overloaded function type"
compile time error is produced; (we can't rely on the Mesonides'
trick, or equivalent for free functions, because they require
to know the function name in advance); this is the same behaviour
followed by boost.function;
note: when I say that a function member signature is included in
"ss" I actually mean that the signature of it's `equivalent`
free function is included in "ss";
- if the passed functor "f" is a function object (possibly overloaded
or polymorfic) then:
- let be "rs" the set of signatures that are defined by its overload
resolution set (or it would be better to say "by the overload
resolution set of f::operator()" ); note that for a polymorfic
object function "rs" is an infinite set;
- if the intersection between "rs" and "ss" is empty the assignment
fails and a compile time error is produced;
- if the intersection between "rs" and "ss" is not empty then the new
target (i.e. "f") overwrites all the targets related to the
signatures included in the intersection.
I hope to have answered to your question.
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