opCast!bool

[Jonathan M Davis]

On Tuesday, January 03, 2012 17:41:12 simendsjo wrote:
> I guess this is as designed, but I'll ask anyway.
> 
> http://dlang.org/operatoroverloading.html#Cast says an expression is
> rewritten to opCast "whenever a bool result is expected".
> 
> This is true for
> if(e) somethingElse
> and e && somethingElse
> 
> , but not for other parts.
> assert(cast(bool)e == true); // explicit cast works
> assert(e == true); // Error: incompatible types for ((s) == (false)):
> 'S' and 'bool'
> 
> is(typeof(e) : bool); // false

Yeah. It's the same for built-in types. Take arrays and pointers for example. 
They don't implicitly convert to bool, but when you use them in a condition, 
they implicitly convert to bool (true if they're non-null, false if they're 
null). If you want implicit conversion in general, then you need to use alias 
this.

- Jonathan M Davis