static foreach issues

[Psychological Cleanup via Digitalmars-d]

On Wednesday, 6 September 2017 at 05:23:47 UTC, Ali Çehreli wrote:
> On 09/05/2017 07:05 PM, Psychological Cleanup wrote:
> > Nesting static foreach and using enum has latent problem.
> >
> > static foreach()
> >   static foreach()
> >   {
> >      enum A = ;
> >   }
> >
> > compiler complains because A is defined multiple times by the
> outer most
> > foreach.
>
> That's understandable as there are multiple As dropped into 
> code.
>
> > To fix this
> >
> > static foreach()
> >   static foreach()
> >   {
> >      {
> >         enum A = ;
> >      }
> >   }
> >
> > But then compiler complains about unexpected { if in a scope
> where
> > normal {}'s are not expected.
>
> Can you demonstrate with compilable code? Doing what you 
> describe works for me:
>
> void main() {
>     static foreach(i; 0 .. 3)
>         static foreach(j; 0 .. 3)
>         {
>             {
>                 enum A = i * j;
>             }
>         }
> }
>
> Ali

Yes, but I said you can't do that. Put the static foreaches 
outside main in to a block where one can't simply do {} and it be 
valid.

You see, the point is that

static foreach
    static foreach
    {

    }

works at the module level

static foreach
    static foreach
    {
        enum a = ;
    }

fails because of multiple a's


so

static foreach
    static foreach
    {
       {
          enum a = ;
       }
    }

to solve that(which, in your given example, works inside main) 
but fails at the module scope because the { }'s we used to solve 
the first problem created a new problem. The two methods are 
mutually exclusive but both are required.


Sure, I could wrap stuff around a function, but what if I'm using 
them for code generation inside a class? I have to use the extra 
{ } to prevent the enum error but then I get a new error about 
the { }.


class X
{
    static foreach
      static foreach
      {
        // fails, multiple a
        enum a = ; // part of class generation code like 
generating functions

      }
}


class X
{
    static foreach
      static foreach
      {
        // fails, { } block inside a class.
        {
            enum a = ; // part of class generation code like 
generating functions
        }

      }
}




it works fine if we use it in a function because we can have { } 
in functions without problems.

Do you not see the contradictory nature? { } required but { } 
forbidden.