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digitalmars.D.learn - Function accepts const ubyte[], const char[], immutable ubyte[],

reply zabruk70 <sorry noem.ail> writes:
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?


And 2nd question:

what if additionally to written above, function shuld return 
ubyte[] or char[] ?
can compiler guess what return type need from code?
something like:

char[] cc = myFunc()
ubyte[] bb = myFunc()

Thanks.
Jan 10 2016
next sibling parent reply Tobi G. <gruen_tobias web.de> writes:
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
Jan 10 2016
parent zabruk70 <sorry noem.ail> writes:
On Sunday, 10 January 2016 at 11:13:00 UTC, Tobi G. wrote:

 ubyte[] myFunc(T1,T2)(T1[] a, T2[] b)


Tobi, big thanks!!!
I should learn templates...
Jan 10 2016
prev sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Sunday, 10 January 2016 at 10:10:46 UTC, zabruk70 wrote:

 void myFunc(char[] arg) { ubyte[] arg2 = cast(ubyte[]) arg; ...}



void myFunc(const(void)[] arg) {
    const(ubyte)[] arg2 = cast(const(ubyte)[]) arg;
    // use arg2
}


A `const(void)[]` type can accept any array as input. void[] is 
any array, const means it will take immutable, const, and mutable 
as well. Then you cast it to one type to use it.


 what if additionally to written above, function shuld return 
 ubyte[] or char[] ?


That depends on what you're doing, but you might also just want 
to return const(void)[], which the user will have to cast to 
something for them to use.
Jan 10 2016
parent zabruk70 <sorry noem.ail> writes:
On Sunday, 10 January 2016 at 14:17:28 UTC, Adam D. Ruppe wrote:

 A `const(void)[]` type can accept any array as input. void[] is


Ah, how i can forget about void[] !
Thanks Adam!
Jan 10 2016