On Friday, 28 November 2014 at 19:45:48 UTC, H. S. Teoh via
Digitalmars-d-learn wrote:
This syntax is a little confusing, but basically the ":" there
is saying
"this type, when instantiated with the following pattern,
produces a
valid type". Essentially it's equivalent to:
Point!T getResponse(T)(string question)
if (is(typeof(Point!T))) // i.e., Point!T is a valid type
{
...
}
Is there a typo here? This version doesn't compile with the
original call: auto pt = getResponse!(Point!int)("point");
Yes, because D does not support overlapping template overloads.
But I thought the original example has ovelapping templates.
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)
{
writef("%s (%s): ", question, T.stringof);
T response;
readf(" %s", &response);
return response;
}
// The specialization of the function template for Point
T getResponse(T : Point)(string question)
{
writefln("%s (Point)", question);
auto x = getResponse!int(" x");
auto y = getResponse!int(" y");
return Point(x, y);
}
auto center = getResponse!Point("Where is the center?");
Doesn't getResponse!Point match both declarations?
