Can't understand templates

[Ali Çehreli via Digitalmars-d-learn]

On 11/28/2014 10:26 PM, Sly wrote:

 > I still don't understand how to
 > read this signature:
 > Point!T getResponse(T: Point!T)(string question)

The following is what makes sense to me.

Sorry for going step by step but I think it helped me understand your 
question. (See item 3 below.)

1) Point!T is the return type. Although T is unknown at this point, we 
will wait a little because it may be a template parameter.

Also, according to the syntax of Point!T, Point is apparently a 
template. So, this function will return the T instantiation of Point, 
whatever T will be deduced to be in a moment.

2) getResponse is the name of the function

3) The first set of parameters is the template parameters:

(T: Point!T)

The meaning: T is a type and this specialization is for Point!T.

Ok, I think I finally understand your original question. I agree that it 
doesn't make sense to say "T is a type and this specialization is for 
Point!T". I think we need to read it backward in this case: "This 
specialization is for Point!T. If so, deduce T from that." So, if 
getResponse is instantiated with Point!int, then T is deduced to be int.

4) The instances of this function template take string parameter.

Ali