On 11/28/2014 12:36 PM, Sly wrote:
> Let's take a simpler example from earlier in the tutorial, where
> Point is a non-template struct:
>
>
> // The general definition of the function template (same as
> before)
> T getResponse(T)(string question)
> {
[...]
> }
That definition would work with any type T. So, it is general: it
accepts any type.
> // The specialization of the function template for Point
> T getResponse(T : Point)(string question)
> {
[...]
> }
That definition is for T that matches Point (i.e. Point itself in this
example). So, it is special: it accepts only that type.
> auto center = getResponse!Point("Where is the center?");
>
> Doesn't getResponse!Point match both declarations?
True but the call is dispatched to the most special of all of the
matches. It is very briefly explained through a reference to C++:
"The template picked to instantiate is the one that is most specialized
that fits the types of the TemplateArgumentList. Determine which is more
specialized is done the same way as the C++ partial ordering rules. If
the result is ambiguous, it is an error."
See the "Specialization" heading here:
http://dlang.org/template.html
Ali
