Using "cast(enum)" for explicit request of ctfe

[monarch_dodra]

On Wednesday, 4 December 2013 at 13:45:35 UTC, Jakob Ovrum wrote:
> On Wednesday, 4 December 2013 at 13:16:35 UTC, monarch_dodra 
> wrote:
>> Problem is that doing this returns an immutable type, which 
>> isn't quite the same as a ctfe variable (which was the initial 
>> goal, as far as I'm concerned)
>
> Immutable "global" variables with initializers are readable at 
> compile-time (as the initializers are required to be readable 
> at compile-time). I don't know what you mean by "CTFE variable".

I mean that:

auto a = eval!(1 + 2);
a += 1; // <= cannot modify immutable expression 3

Should work.

Or that:

auto arr = eval!(iota(0, 10).array());
//arr is expected to be int[]
//NOT immutable(int[])
arr[0] = 10; //Error: cannot modify immutable expression arr[0]

Long story short, just because something is pre-calculated with 
CTFE doesn't mean it can't be mutable.

For example:
enum a10 = iota(0, 10).array();
auto arr1 = a10;
auto arr2 = a10;
assert(arr1 !is arr2);
assert(arr1 == arr2);
arr1[0] = 10;
assert(arr1 != arr2);


> Using enum has issues, as elaborated upon by Don in this 
> enhancement request[1] (for reference; I'm sure you remember 
> them).
>
> [1] http://d.puremagic.com/issues/show_bug.cgi?id=10950

I absolutely remember that. But I still believe that is a *bug*, 
and not an enhancement request. Buggy behavior should not dictate 
our design.