Assert

[David B. Held]

Walter Bright wrote:
> David B. Held wrote:
>> Obviously there's a thousand ways to riff on that basic idea, but try 
>> writing this function in D.  As you can see, it's essentially a form 
>> of assert().
> 
> Done:
> 
> T Enforce(T)(T p,  lazy char[] msg)
> {
>     if (!p)
>     throw new Exception(msg());
>     return p;
> }
> 
> http://www.digitalmars.com/d/1.0/lazy-evaluation.html

Yeah, that's what everyone else said.  But what it is missing is 
*stringizing of the condition*, so that you can put it into the message. 
  For Enforce(), that's not as important; but for a custom assert(), it is.

Dave