Can't understand templates

[Sly via Digitalmars-d-learn]

You miss another definition which introduces a conflict:
T getResponse(T)(string question)
{...}

On Saturday, 29 November 2014 at 17:20:42 UTC, Meta wrote:
> On Saturday, 29 November 2014 at 11:07:34 UTC, Sly wrote:
>> On Saturday, 29 November 2014 at 09:11:51 UTC, Ali Çehreli 
>> wrote:
>>
>>> Point!T getResponse(P : Point!T, T)(string question)
>>> {
>>>   // ...
>>> }
>>>
>>
>> This doesn't work because now this definition has 2 parameters 
>> P
>> and T. I have to specify both like this: auto pt =
>> getResponse!(Point!int, int)("point");  which of course defeats
>> the purpose. Otherwise I have ambiguity error:
>
> Not true, T is inferred based on the the type Point has been 
> instantiated with, letting you emit the second template 
> argument. The following code works:
>
> struct Point(T)
> {
> 	T x;
> 	T y;
> }
>
> P getResponse(P: Point!T, T)(string message)
> {
> 	return P(T.init, T.init);
> }
>
> void main()
> {
> 	import std.stdio;
> 	
>         //T is inferred to be int automatically
> 	writeln(getResponse!(Point!int)("test"));
> }