Re: Problem with using std.math: abs and std.complex: abs at the same time

[Simen Kjærås via Digitalmars-d-learn]

On Wednesday, 18 September 2019 at 13:24:05 UTC, berni wrote:
On Wednesday, 18 September 2019 at 12:37:28 UTC, Simen Kjærås 
wrote:
How to resolve this, though? The simplest solution is to not 
use selective imports:

    import std.math;
    import std.complex;

    writeln(abs(complex(1.0,1.0)));
    writeln(abs(1.0));

That works. But: I'm trying to write some code for math.d and 
when I put this code inside math.d it doesn't work anymore. 
Also removing "import std.math" or moving it after the other 
import, did not help.

So what you have is basically this?

import std.stdio;

float abs(float f) {
    return f >= 0 ? f : -f;
}

unittest {
    import std.complex : complex, abs;

    auto a = complex(1.0,1.0);
    auto b = 1.0f;

    writeln(abs(a));
    writeln(abs(b));
}

That does indeed fail to compile, and there's no easy way to 
introduce the module-level abs() function to the scope. Again 
though, MergeOverloads to the rescue:

float abs(float f) {
    return f < 0 ? -f : f;
}

unittest {
    import std.complex : complex, cabs = abs;
    alias abs = MergeOverloads!(cabs, .abs);
    abs(1);
    abs(complex(1,1));
}

template MergeOverloads(T...) {
    static foreach (E; T)
        alias MergeOverloads = E;
}

--
  Simen