Template Prerequisite proposal

[Robert Fraser]

DavidL Wrote:
> For common case:
> 
> template k(T)
> {
> 	static assert(T.max==int.max);
> }

To test types, you could just use the "is" expression (unless there was a special reason you were comparing to int.max?):

static assert(is(T == int)); // Compilation will fail if T is not int
static assert(is(U : Lion)); // Compilation will fail if U is not implicitly castable to Lion

> 
> template a(T)
> {
> 	void func(T t)
> 	in
> 	{
> 		mixin k!(T);
> 	}
> 	body
> 	{
> 	}
> }
> 
> mixin a!(int);
> 
> 
> so there's a unified way of mixin template for prerequisite checking.
> 
> I hope if there's any way of restrict template writer write code which only uses things which are checked in the prerequisite checking.

I'm not sure exactly what you mean. Example?