Re: iterate over variadic

[Lamex via Digitalmars-d-learn]

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));
}