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 | Posted by Simen Kjaeraas |  Permalink Reply |
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Simen Kjaeraas 
| https://issues.dlang.org/show_bug.cgi?id=20226
--- Comment #1 from Simen Kjaeraas <simen.kjaras@gmail.com> ---
Note that even though changing the order of imports makes the above code
compile, that's because std.math's abs() implementation ends up being the one
available, and calling abs() on e.g. a Complex!float would fail in that case
(but would compile in the above example).
This same issue occurs when importing a function that also exists in a parent scope:
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));
}
In a non-function scope, the solution is to use an alias:
float abs(float f) {
return f < 0 ? -f : f;
}
struct S {
import std.complex : complex, abs;
alias abs = .abs;
unittest {
abs(1);
abs(complex(1,1));
}
}
However, this doesn't work inside functions:
float abs(float f) {
return f < 0 ? -f : f;
}
unittest {
import std.complex : complex, abs;
alias abs = .abs; // declaration abs is already defined
}
A workaround exists in using a non-function scope to merge the overload sets:
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;
}
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