Function accepts const ubyte[], const char[], immutable ubyte[], immutable char[]

[Tobi G. via Digitalmars-d-learn]

On Sunday, 10 January 2016 at 10:10:46 UTC, zabruk70 wrote:
> Hello.
>
> 1st Novice question:
>
> i want function, operates sometimes with char[], sometimes with 
> ubyte[].
> internally it works with ubyte.
> i can use overloading:
>
> void myFunc(ubyte[] arg) {...};
> void myFunc(char[] arg) { ubyte[] arg2 = cast(ubyte[]) arg; ...}
>
> It is OK. But i want 2 params (arg1, arg2),
> so i need write 4 overloading functions.
>
> I fill templated needed, can anybody show me the way?

No you actually don't have to write all possible overloads.

For example:
(surely not the best solution)

import std.traits;

ubyte[] myFuncImpl(ubyte[] a, ubyte[] b)
{
	return a ~ b;
}

ubyte[] myFunc(T1,T2)(T1[] a, T2[] b)
	if(is(Unqual!T1 == ubyte) || is(Unqual!T1 == char)
		|| is(Unqual!T2 == ubyte) || is(Unqual!T2 == char))
{
	return myFuncImpl(cast(ubyte[]) a, cast(ubyte[]) b);
}


> And 2nd question:
>
> what if additionally to written above, function shuld return 
> ubyte[] or char[] ?
> can compiler guess what return type need from code?

No. Your function call signature would be completely the same..

The way to do this is to make the function a template and pass 
the return parameter to it.
So you're able to do something like:

auto val = myReturnFunc!int();


togrue