enum to string

[Daniel Keep]

Ary Borenszweig wrote:
> Lionello Lunesu wrote:
>>
>> "Brad Roberts" <braddr at bellevue.puremagic.com> wrote in message
>> news:alpine.DEB.2.00.0903121755240.4513 at bellevue.puremagic.com...
>>> That said, I don't think this really helps the desired usecase much. 
>>> It's
>>> useful, don't get me wrong, but still requires code to build up the
>>> bi-directional translations.  Or am I missing something?  Seems to be
>>> happening to me a lot lately, so I'm very prepared to be wrong here too.
>>> :)
>>
>>
>> You're not wrong :)
>> The problem is that the foreach variable is not evaluatable to a
>> compile-time string. I don't know why, but I'll figure it out tonight.
>>
>> I've also managed to convert an enum to an AssocArrayLiteralExp* (with
>> the name/string as the key and the value/int as the value) but it
>> seems that it cannot be foreached at compile time, even if it's a
>> literal expression. But hell, I've spent about 1 hour browsing through
>> dmd's code, so I'm pretty sure it's possible with a little more research.
> 
> Can you foreach at compile-time? I thought you could only do that in
> CTFE (or templates?). Maybe that's why it's not working. How do you do
> it to pragma msg the members of a struct?
> 
> I remember someone proposed "static foreach" some time ago...

We have a sort-of static foreach.  The trick is that the aggregate HAS
to be a tuple.  When in doubt, you can always fall back on the following
construct:

template Tuple(T...)
{
    alias T Tuple;
}

template Range(int n)
{
    static if( n <= 0 )
        alias Tuple!() Range;
    else
        alias Tuple!(Range!(n-1), n-1) Range;
}

void blah()
{
    // Note that static foreach ONLY works inside a function
    foreach( i ; Range!(n) )
    {
        // do stuff with i, which should be a const int
    }
}

There have been times when directly accessing some CT construct would
make the compiler choke, but going via an index worked fine.

    -- Daniel