Version block "conditions" with logical operators

[Artur Skawina via Digitalmars-d]

On 05/10/16 13:48, Tomer Filiba via Digitalmars-d wrote:
> On Tuesday, 10 May 2016 at 11:12:58 UTC, Tomer Filiba wrote:
>> Alternatively, an isVersion(x) predicate that I could use in a static if could do the trick
> 
> Well, I've come up with
> 
> template isVersion(string ver) {
>     mixin(format(q{
>         version(%s) {
>             enum isVersion = true;
>         }
>         else {
>             enum isVersion = false;
>         }
>     }, ver));
> }
> 
> pragma(msg, isVersion!"foo");     // false
> pragma(msg, isVersion!"assert");  // true
> 
> But it feels hackish too

It is a hack; the main problem being that the check happens at
the `isVersion` definition, and not where it's used. But, if you
only care about "global" identifiers, you can just use something
like this:

-----------------------------------------------------
   module mver;

   struct ver {
      template opDispatch(string M) {
         mixin(`
            version(`~M~`) enum opDispatch = true;
            else           enum opDispatch = false;
         `);
      }
   }
-----------------------------------------------------
   import mver;

   static if (ver.linux && !ver.D_LP64) {
      /* ... */
   }
-----------------------------------------------------

artur