pure, safe and generalized attributes

[Knud Soerensen]

Janice Caron wrote:
> On 05/04/2008, Knud Soerensen <4tuu4k002 at sneakemail.com> wrote:
>> Janice Caron wrote:
>>
>>> On 05/04/2008, Knud Soerensen <4tuu4k002 at sneakemail.com> wrote:
>>  >> You could also ague that it is not necessary because
>>  >>  attributes can only appear in certain places
>>  >>
>>  >>  only in function, class, struct and module declarations.
>>  >
>>
>>>     KilroyWasHere:
>>  >
>>  > Is that an attribute or a label?
>>
>> "KilroyWasHere" is the label for the attribute
>>  that this place was inspected by Kilroy
>>
>>  Why do you ask ??
> 
> I was trying to make the point that D has a context-free grammar, and
> that an identifier followed by a colon, where you might expect to find
> a statement or a declaration, might be ambiguous.
> 
> In hindsight, I might have jumped too fast. It might be possible to
> tell the difference because: if you're expecting a statement, it's a
> label; if you're expecting a declaration, it's an attribute.
> 
> However, the point still stands. Allowing arbitrary identifiers as
> attributes is /bound/ to confuse the parser somewhere along the line,
> unless we explicitly indicate to the compiler that this identifier is
> an attribute.

I see that the D manual already have something called attributes
it might have been confusing you.

Maybe if i use the word constrain, for what we talking about is a way to
define code constrains.

We have this now i D
ModuleDeclaration:
 module ModuleName ;

ClassDeclaration:
  class Identifier BaseClassList(opt)  ClassBody

FunctionDeclaration: (I didn't find this in the manual)
 type Identifier(Parameters) FunctionBody

With constrains we will have this
ModuleDeclaration:
 module ModuleName ConstrainList(opt);

ClassDeclaration:
  class Identifier BaseClassList(opt)  ConstrainList(opt) ClassBody

FunctionDeclaration:
 type Identifier(Parameters) ConstrainList(opt) FunctionBody

Hope this helps

Knud