On Thursday 11 March 2004 06:19 am, Peter Dimov wrote:
Douglas Gregor wrote:
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.
I find your suggestion intriguing and appealing, in a certain "clever hack" way, but you miss my point. I am not talking about keeping Lambda compatible with what Bind does now. What I have in mind is an extended Bind that supports !bind, bind ==, bind !=. That Bind is what I want to be compatible with Lambda. At the moment, your idea seems too costly to implement in Bind, and I see no corresponding benefits, but I'll keep it in mind as a potential alternative.
It's not really an alternative. We have two possible reasons that a binding operator would want to overload operator==: for comparison or for creating a function object. I'm just saying we don't have to choose between the alternatives, because we can overload operator== to return a function object that also has a conversion to bool that compares the stored function objects. The benefit is that we don't need to introduce a "function_equal" to compare functions and we can still choose whether to support (bind(f, _1) == bind(g, _1))(5) Doug