Daniel Walker wrote:
On 4/28/07, Peter Dimov <pdimov@mmltd.net> wrote:
Daniel Walker wrote:
So, you mean that Bind is definitely going to overload the relational operators.
Bind already overloads the relational operators:
Aha, that was the source of my confusion. I'm not so worried about bind(f, _1) < x. This already works even when the lambda header is included. Moving forward, I think breaking this code can be avoided.
I'm worried about bind(f, _1 < x) or bind(f, _1) < _2.
bind(f, _1) < _2 is also handled by Bind.
in more limited contexts. It is trivial to extend this overloading to work on expressions that involve no bind calls such as _1 == 5, _1 > _2 or !_4 - provided that the placeholders aren't inline functions, of course. :-)
It's also trivial to make lambda generate is_bind_expression specialized functors. I think one or the other of the libraries should take care of this use-case but not both, just to avoid the head aches.
This is how I think it should work: boost::bind(...) relop ...: Bind (as today) !boost::bind(...): Bind _1 relop ...: Bind, translates to boost::bind( __relop(), _1, ... ) !_1: Bind, translates to boost::bind( __not(), _1 ) _1 + ...: Lambda (based on is_placeholder<>) ll::bind( f, _1 ): as above boost::bind(...) + ...: Lambda (based on is_bind_expression<>) ll::_1 relop ...: Lambda or Bind - TBD !ll::_1: Lambda or Bind - TBD boost::bind( f, _1 + _2 ): won't work with boost::bind; should work with std::bind.