On Tuesday, 14 July 2015 at 14:02:46 UTC, jmh530 wrote:
Thanks for posting that. I figured out the issue. Before you
had recommended that I use
alias cos = std.math.cos;
I had kept that text in. When I removed it, everything worked
just fine. I'm still not sure I grasp the subtleties of alias
when used with templates.
Oh that's another goodie. So you had a situation like this:
----
import std.math;
alias cos = std.math.cos;
mixin template t()
{
void cos(real[] arr) {/* ... */}
}
mixin t!();
void main()
{
cos([1, 2, 3]);
}
----
This fails with "Error: None of the overloads of 'cos' are
callable using argument types (int[])".
The problem is that template mixins cannot add to existing
overload sets. The spec says: "If the name of a declaration in a
mixin is the same as a declaration in the surrounding scope, the
surrounding declaration overrides the mixin one" [1]. That means,
the `cos` from `alias cos = std.math.cos;` completely overrides
the one from `mixin t!();`. I guess this is a measure against
function hijacking again.
I'm not sure if it's supposed to work like it does when the alias
is removed, two implicitly imported/generated symbols forming an
overload set. But I can't immediately see a problem with it
either.
[1] http://dlang.org/template-mixin.html - see "Mixin Scope"
