On Sat, Dec 01, 2018 at 01:17:55AM +0000, solidstate1991 via
Digitalmars-d-learn wrote:
> After some refactoring, there are four functions sharing the same name
> (technically four, but LDC didn't complain about them):
>
> @nogc void blitter(T)(T* src, T* dest, size_t length){...}
>
> and
>
> @nogc void blitter(T)(T* src, T* dest, size_t length, T* mask){...}
>
> I need the first one, but at compilation time I get the following
> error:
>
> pixelperfectengine\src\PixelPerfectEngine\graphics\layers.d(61,30): Error:
> template CPUblit.composing.blitter matches more than one template declaration:
> ..\..\..\AppData\Local\dub\packages\cpublit-0.2.3\cpublit\src\CPUblit\composing.d(2006,19):
> blitter(T)(T* src, T* dest, size_t length)
> and
> ..\..\..\AppData\Local\dub\packages\cpublit-0.2.3\cpublit\src\CPUblit\composing.d(2274,19):
> blitter(T)(T* src, T* dest, size_t length, T* mask)
For non-template overloaded functions, you can get the address by
casting the function pointer, e.g.:
void fun(int size) {
writeln("1");
}
void fun(int size, float z) {
writeln("2");
}
auto p1 = cast(void function(int)) &fun;
auto p2 = cast(void function(int, float)) &fun;
auto p3 = cast(void function(int, string)) &fun;
p1(0); // prints "1"
p2(0, 0f); // prints "2"
p3(0, ""); // prints "1" (!)
It's sorta weird when the cast doesn't match any overload; the compiler
seems to just arbitrarily select the first one.
However, for template functions, casting isn't enough; you need
__traits(getOverloads):
alias ovs = __traits(getOverloads, myModule, "gun", true);
foreach (ov; ovs) {
writeln(ov.stringof);
}
prints:
gun(T)(T t, int size)
gun(T)(T t, int size, float z)
But actually coaxing the address out of the function is rather ugly:
// These don't work:
//auto q = &ovs[0]!int;
//auto q = &(ovs[0]!int);
//auto q = &(ovs[0])!int;
// ... etc.
// But this does:
alias ov1 = ovs[1];
auto q = &ov1!int;
q(0, 1, 1f); // prints "4"
However, there appears to be a bug: if you try to access the first
overload, it doesn't work again!
// But this does:
alias ov0 = ovs[0]; // NG: compile error!
auto q = &ov0!int;
q(0, 1, 1f);
Sounds like a compiler bug should be filed. :-/
I tried to hack it by using AliasSeq to insert a dummy first element to
the sequence then using [1] to access the first overload, but got the
same error. I guess internally somehow the compiler isn't treating the
first overload case correctly, independently of its position in the
tuple / AliasSeq.
T
--
Nearly all men can stand adversity, but if you want to test a man's character,
give him power. -- Abraham Lincoln
