On Wednesday 10 March 2004 07:41 am, Peter Dimov wrote:
Douglas Gregor wrote:
I'd think that this is the right expectation for Lambda, but not for FC++ or Bind. Not that I'm helping any :)
No, I don't think so. Expressions that are valid for both Bind and Lambda should have the same semantics. And in fact, this is not just theory:
Having Lambda's == and != operators return function objects convertible to bool would keep Lambda's semantics a superset of Bind's semantics.
More generally, I think it's not a good idea to try to create "function equality" with operator==. I didn't participate in any of the earlier discussions, but I think that if you want to register/unregister function objects with an event handler, for instance, you should use a separate "handle" object to keep track of "function object identity".
The problem is that there are a whole lot of use cases for equality of function objects, and people really want them. The especially want
delegate<void()> f; f += some_function_object; // connect f -= some_function_object; // disconnect
There is no mention of operator== anywhere in the above, though.
Right. The basic idea of "-=" is that it uses == to find connected targets equal to some_function_object and disconnects them. Of course, it could use function_equal or anything else, but I do feel that == is most natural. Doug