std.random.uniform for enums

[Jakob Ovrum]

On Thursday, 13 February 2014 at 02:02:38 UTC, Anton wrote:
> I'm confused about how to use random.uniform to select a member 
> of an enum.
>
> Say I have an enum like
>
>     enum Animals
>     {
>       cat  = 0,
>       dog = 1,
>       chimpanzee = 2
>     }
>
> I want to select a random animal. So far I've been trying to do 
> uniform(Animals), but every time I try to compile that, I get a 
> "does not match any function template declaration" error.
>
> Am I misunderstanding how this function is meant to be used?

The problem with using `uniform` for enums is that not all enums 
are sequential without holes, which would make the `uniform` 
implementation quite non-trivial if it were to try to handle 
enums generically.

If you know your enum is sequential and doesn't have any holes, 
assume responsibility for that fact with a cast:

---
enum Animals
{
	cat = 0,
	dog = 1,
	chimpanzee = 2
}

void main()
{
	import std.random, std.stdio;

	foreach(immutable _; 0 .. 10)
		writeln(cast(Animals)uniform!"[]"(Animals.min, Animals.max));
}
---