How can we iterate over a variadic and have it's index. I'll do different things depend on if it's an even or odd index, but seems to be no way to get it.

10.07.2017 01:21, FoxyBrown пишет:
> How can we iterate over a variadic and have it's index. I'll do different things depend on if it's an even or odd index, but seems to be no way to get it.
> 

auto foo(Types...)()
{
	foreach(T; Types)
	{
		// do what you need
	}
}
index could be added like usual

On Sunday, 9 July 2017 at 22:21:59 UTC, FoxyBrown wrote:
> How can we iterate over a variadic and have it's index. I'll do different things depend on if it's an even or odd index, but seems to be no way to get it.


import std.stdio;
import std.typecons, std.meta;

template indexedAllSatisfy(alias F, T...)
{
    bool doTest()
    {
        bool result = true;
        import std.range: iota;
        foreach(i; aliasSeqOf!(iota(0, T.length)))
            result &= F!(T[i], i, T.length);
        return result;
    }
    enum indexedAllSatisfy = doTest();
}

unittest
{
    template evenIntString(T, int index, int length)
    {
        static if (length & 1)
            enum evenIntString = false;
        else static if (index & 1)
            enum evenIntString = is(T == string);
        else
            enum evenIntString = is(T == int);
    }

    static assert(indexedAllSatisfy!(evenIntString, int, string, int, string));
    static assert(!indexedAllSatisfy!(evenIntString, int , string, char, Object));
}

On Sun, Jul 09, 2017 at 10:21:59PM +0000, FoxyBrown via Digitalmars-d-learn wrote:
> How can we iterate over a variadic and have it's index. I'll do different things depend on if it's an even or odd index, but seems to be no way to get it.

Easy:

	auto func(Args...)(Args args) {
		foreach (i, arg; args) {
			if (i % 2) {
				// even
				... // do something with arg
			} else {
				// odd
				... // do something with arg
			}
		}
	}


T

-- 
"Real programmers can write assembly code in any language. :-)" -- Larry Wall

On 07/10/2017 08:31 PM, H. S. Teoh via Digitalmars-d-learn wrote:
> 			if (i % 2) {
> 				// even

odd

> 				... // do something with arg
> 			} else {
> 				// odd

even

> 				... // do something with arg
> 			}