On Tuesday 09 March 2004 05:26 pm, Brian McNamara wrote:
In my opinion, lambda(x) { return f(x) == g(x) }. is best. Whenever I see a placeholder, I expect the whole expression (modulo operator precedence and "constant(foo)" issues) to get lambda-ized, and thus I expect operator== to create a lambda expression. (I dunno if this is the 'right' expectation to have, given the way the libraries work now, but I think it is a reasonable/simple 'ideal' expectation.)
I'd think that this is the right expectation for Lambda, but not for FC++ or Bind. Not that I'm helping any :)
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
(The whole idea of "f==g" being meaningful for two functions is a little bit fishy to me, but this is probably more of a personal bias than anything I can defend objectively.)
I held to that philosophy for a long time, but the use cases are stacked against us :) Doug