Hi,

i'm trying to create a dynamic vertex format for opengl, defined at compiletime by a struct

e.g. struct Vertex {float[3] position, float[3] normal}

i can get the name of all members with this:
auto b = [ __traits(allMembers, VertexType) ];

but i can't iterate them at compiletime because there is no static foreach?
foreach(e; b) {
  alias tt = typeof(__traits(getMember, VertexType, e)); // not working
  writeln(tt.sizeof);
}

since i need to setup vertexpointers for opengl at runtime my next question? - is it possible to evaluate the traits also at runtime? but i'd also like to know how i can iterate them at compiletime

thx in advance :)

On Tue, 19 Aug 2014 18:15:33 +0000, ddos wrote:

> since i need to setup vertexpointers for opengl at runtime my next question? - is it possible to evaluate the traits also at runtime? but i'd also like to know how i can iterate them at compiletime
> 
> thx in advance :)

Take a look at this example: http://dpaste.dzfl.pl/2fdea78a49b6

A foreach becomes compile-time whenever the aggregate is a purely compile- time construct such as a tuple.

On Tuesday, 19 August 2014 at 18:25:24 UTC, Justin Whear wrote:
> On Tue, 19 Aug 2014 18:15:33 +0000, ddos wrote:
>
>> since i need to setup vertexpointers for opengl at runtime my next
>> question? - is it possible to evaluate the traits also at runtime? but
>> i'd also like to know how i can iterate them at compiletime
>> 
>> thx in advance :)
>
> Take a look at this example:
> http://dpaste.dzfl.pl/2fdea78a49b6
>
> A foreach becomes compile-time whenever the aggregate is a purely compile-
> time construct such as a tuple.

thank you!

>> A foreach becomes compile-time whenever the aggregate is a purely compile- time construct such as a tuple.

Yeah, I think you transformed it into a runtime array by using [ ... ]. Tuples with compatible types can be 'downgraded' to arrays that way. But there is no need to: tuples are iterable, indexable and slice-able in D.

import std.stdio;

struct Vertex {float[3] position; float[3] normal;}

void main() {
    foreach(e; __traits(allMembers, Vertex)) {
        alias tt = typeof(__traits(getMember, Vertex, e)); // worksforme
        writeln(tt.sizeof);

    }
}