Improving version(...)

[Simen kjaeraas]

Don <nospam at nospam.com> wrote:

> My opinion (a significant departure from the current situation,  
> unfortunately):
> It should be possible to define version identifiers with booleans.
>
> version EnableFeatureX = !Lite && !Demo;

This looks nice to me, except that the rhs looks like normal code. It
gives me the feeling that version foo = sqrt(bar) should work.

Perhaps version foo = version( bar && !baz ); is better. I'm not sure.


> Possibly:
> * make it illegal to define a version identifier from inside a version  
> {} block.

This would break existing code, and it feels logical to write code like
this:

version( foo ) {
     // quite a few lines of dependent code
     version = bar;
}

Of course, the result is cleaner:

version( foo ) {
     // quite a few lines of dependent code
}
version bar = foo;

So I'm a bit torn. Wait, getting a brain wave again....

Ahh. Make that a ++votes.


> * disallow duplicate version definitions.

Absolutely.


> * require declarations for all version identifiers. Versions which are  
> set from the command line should be explicitly declared, eg:
> version Lite = extern;
> version Demo = extern;
>
> That would make creating a bird's nest impossible.
> And currently, you can make a typo like:
> version(Linix) {}
> and it compiles happily. I don't like that. Especially when we have  
> builtin names like D_Inline_Asm_X86_64!

This is an awesome idea. ++votes


-- 
Simen