The following program compiles, and does what you'd expect:

struct A {
    int a;
}

pure int func( ref A a )
{
    return a.a += 3;
}

As far as I can tell, however, it shouldn't. I don't see how or why func can possibly be considered pure, as it changes a state external to the function.

What am I missing? Or is this just a compiler bug?

Shachar

On Monday, 25 August 2014 at 06:27:00 UTC, Shachar wrote:
> The following program compiles, and does what you'd expect:
>
> struct A {
>     int a;
> }
>
> pure int func( ref A a )
> {
>     return a.a += 3;
> }
>
> As far as I can tell, however, it shouldn't. I don't see how or why func can possibly be considered pure, as it changes a state external to the function.
>
> What am I missing? Or is this just a compiler bug?
>
> Shachar

http://klickverbot.at/blog/2012/05/purity-in-d/