• ddos (18/18) Aug 19 2014 Hi,
• Justin Whear (5/10) Aug 19 2014 Take a look at this example:
• ddos (2/15) Aug 19 2014 thank you!
• Philippe Sigaud via Digitalmars-d-learn (12/14) Aug 19 2014 Yeah, I think you transformed it into a runtime array by using [ ...

"ddos" <oggs gmx.at> writes:

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 :)

Justin Whear <justin economicmodeling.com> writes:

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.

"ddos" <oggs gmx.at> writes:

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!

Philippe Sigaud via Digitalmars-d-learn writes:

 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);

    }
}