Re: [Boost-users] Bind: more convenience operators?

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-06-01 14:17:16

Arno Schoedl wrote:

> Bind has operator! overloaded to allow convenient notting of bound
> functions. Is there a specific reason not to overload all other
> operators in a similar way, for example for defining an AND of two
> predicates f and g as boost::bind( f, _1 ) && boost::bind( g, _1 )?

Yes, there are specific reasons to not overload all operators, not all of 
them showstoppers.

The reason to not overload operator+ and similar is that boost::bind does no 
return type deduction; it always produces a function object with a fixed 
result_type.

The reason to not overload operator||, operator&& and operator, (whose 
return types are known) is that x && y, x || y and x,y are not expressible 
as bind( fn, x, y ) because of the specific requirements of these operators 
for evaluation order and shortcut evaluation. They are still doable, of 
course. If you have a prototype implementation in mind, please do not 
hesitate to show it. :-)