CTFE & template predicates

[anonymous via Digitalmars-d-learn]

On Monday, 4 May 2015 at 11:22:16 UTC, Robert M. Münch wrote:
> Hi, ok, just to better understand this (I have a C++ background 
> (even quite old)): When I want to use some functions I need to 
> specify the type? It's not possible to use T.length() which 
> would compile if T is a string? I thought that it's just 
> generic and I can throw in T.

In template parameter lists, a solitary identifier is a type 
parameter. You can only pass types in those.

In function (pointer) declarations, a solitary identifier is the 
type of the parameter.

In function/delegate literals, a solitary identifier is the name 
of the parameter and the type is inferred. I guess this is what 
you were thinking of.

----
void main()
{
     template t(T) {} /* T is a template type parameter. */
     alias i = t!int; /* It can be instantiated with the type int, 
for example, */
     static assert(!__traits(compiles, t!123)); /* but not with a 
value. */

     void function(int) fp; /* int is the type of the parameter. */
     fp = (x) {}; /* x is the name of the parameter whose type is 
inferred from above. */
}
----