Beginner problem: casting in opCmp override

[Jonathan M Davis]

On Tuesday, July 09, 2013 00:35:32 Ugbar Ikenaki wrote:
> Here's one more question:
> 
> Before I knew that opEquals existed, I tried overloading the
> equality expressions (== and !=) in opBinary using the code
> below. It worked. Why would the overloaded opBinary version get
> called if the equality expressions are held in opEquals? I'm just
> interested in knowing how dmd chooses where to take an expression
> from if it lies in multiple places (e.g. == in opEquals and
> opBinary), even if what I did was just add the == operator to
> opBinary. (Is that what I did there?)
> 
>         override bool opBinary( string op ) ( Rect r ) if( op ==
> "==" ) {
> 		//Check if rectangle coordinates are equal
> 		if( left == r.left && right == r.right && top == r.top &&
> bottom == r.bottom ) {
> 			return true;
> 		} else {
> 			return false;
> 		}
> 	}
> 
> 
> Thanks!

I don't believe that that will ever work. If you want to overload == and !=, 
use opEquals. opBinary isn't used for that. Look at 
http://dlang.org/operatoroverloading.html if you want to see which function to 
use to overload for each operator.

- Jonathan M Davis