template parameters

[Ellery Newcomer]

Christopher Wright wrote:
> Ellery Newcomer wrote:
>> Okay, let me rephrase that:
>>
>> When you have a <something> preceded by a colon in a template value
>> parameter, what are its semantics? Is it the same as a default parameter
>> value? Is it some sort of constraining expression? Is it a vestige?
> 
> void foo(T : int)(T value)
> {
>     // value is implicitly convertible to int
> }
> 
> It can do some pattern matching:
> 
> void foo(T : V[U], V, U)(T dictionary)
> {
>     // I have an associative array
> }
> 
> In D2, it's usually going to be easier to use constraints:
> 
> template foo(T) if (isAssociativeArray!T) {}

Great, it does something specified for a type parameter.

Now what does it do for a VALUE parameter?