compile-time variables?

[BCS]

Reply to Bill,

> Fraser wrote:
> 
>> I'm trying to create a compile-rime ID that can be used in mixins.
>> The code it's used in is auto-generated, so I can't guarantee
>> anything, and need a separate ID each time the mixin is used (the ID
>> is part of the mixed-in string).
>> 
>> Bill Baxter Wrote:
>> 
>>> Fraser wrote:
>>> 
>>>> <snip>
>>>> 
> I see.  Well rule number 1 of CTFE is "no side effects".  So I think
> that pretty much prevents this from working at compile time, since
> storing a state somewhere is definitely a persistent side effect.
> 
> Are these IDs all in one file?  If not, then in any event you're going
> to run into trouble making the IDs unique across files with a
> compile-time technique.
> 
> --bb
> 

const int Baz = 0;
pragma(msg, "#define Baz 0\n")
template Foo(A...)
{
     pragma{msg,"template Foo("~convert_Tuple_To_Args_List_And_Specilization!(A)~"){const 
int Foo = Baz;}\n#define Baz (Baz+1)\n")
}

Use this Foo everywhere you need it (with enough stuff in A to make each 
use unique).
Compile everything, pipe through cpp, recompile with the resulting code in 
place of the original code.

I will now retreat to my lair to repent for that blasphemy. <g>