Hello folks,

Hope everyone is doing fine. Considering the following code, in the first condition, I am extracting the type Point from the slice Point[]. I searched in the std.traits, and could not find a neater solution something like ElementTypeOf!T. Is there any neater solution for it? Thanks in advance.

    static if (isArray!VecPoint){
        VecPoint dummy;
        alias Point = typeof(dummy[0]);
    } else static if (isRandomAccessRange!VecPoint){
        alias ASeq2 = TemplateArgsOf!VecPoint;
        alias Point = ASeq2[0];
    } else
        static assert(0, typeof(VecPoint).stringof ~ " type is not supported");

Ferhat

On Tuesday, 17 August 2021 at 12:21:31 UTC, Ferhat Kurtulmuş wrote:

This one's not in std.traits:

import std.range : ElementType;

struct Point { int x, y; }

unittest {
    Point[] points;
    assert(is(ElementType!(typeof(points)) == Point));
}

Hello folks,

Hope everyone is doing fine. Considering the following code, in the first condition, I am extracting the type Point from the slice Point[]. I searched in the std.traits, and could not find a neater solution something like ElementTypeOf!T. Is there any neater solution for it? Thanks in advance.

On Tuesday, 17 August 2021 at 12:21:31 UTC, Ferhat Kurtulmuş wrote:

This one's not in std.traits:

import std.range : ElementType;

struct Point { int x, y; }

unittest {
    Point[] points;
    assert(is(ElementType!(typeof(points)) == Point));
}

On Tuesday, 17 August 2021 at 12:21:31 UTC, Ferhat Kurtulmuş wrote:

typeof(T.init[0])

Note that std.range.ElementType will probably not give the result you expect for character arrays (such as char[] and wchar[]), due to autodecoding.

Hello folks,

Hope everyone is doing fine. Considering the following code, in the first condition, I am extracting the type Point from the slice Point[]. I searched in the std.traits, and could not find a neater solution something like ElementTypeOf!T. Is there any neater solution for it? Thanks in advance.

     static if (isArray!VecPoint){
         VecPoint dummy;
         alias Point = typeof(dummy[0]);
     } else static if (isRandomAccessRange!VecPoint){
         alias ASeq2 = TemplateArgsOf!VecPoint;
         alias Point = ASeq2[0];
     } else
         static assert(0, typeof(VecPoint).stringof ~ " type is not supported");

On 8/17/21 8:21 AM, Ferhat Kurtulmuş wrote:

     static if (isArray!VecPoint){
         VecPoint dummy;
         alias Point = typeof(dummy[0]);
     } else static if (isRandomAccessRange!VecPoint){
         alias ASeq2 = TemplateArgsOf!VecPoint;
         alias Point = ASeq2[0];
     } else
         static assert(0, typeof(VecPoint).stringof ~ " type is not supported");

If you want the element type of a range (i.e. the thing returned by range.front), you can use ElementType!T (from std.range.primitives).

This returns the element type of the range, which for every array except character arrays, gives you the element type of the array.

If you want always the element type of the array, even for auto-decoded ranges, use ElementEncodingType!T.

If you know it's an array, you can just use Paul's solution.

Your isRandomAccessRange branch seems very suspect.

-Steve