On Saturday, May 26, 2012 13:05:00 Jacob Carlborg wrote:
> On 2012-05-26 01:17, Jonathan M Davis wrote:
> >> Ok I see, thanks. Is that true for fields in structs and global variables as well?
> > 
> > Anyway, I suppose that that's not terribly conclusive, but the lack of ability to have non-transitive const declarations is a bit of a problem when dealing with extern(C) functions given that it has behaviors that D _doesn't_ have. As far as I can see, whether constifying the whole thing or making it all mutable makes more sense really depends on what the C function is doing and how it's called, which naturally doesn't go well with a tool like you're creating. You'll probably have to go with what is _least_ likely to cause bugs and then let the programmer adjust it as needed.
> > 
> > - Jonathan M Davis
> 
> What do you think about translating the C const to D where possible and then just leave it mutable in all other cases. Then assuming the C code will not cast away const. A user is always free to edit the bindings manually.

That seems like a good approach, since then you're not marking things as const in D that C would consider mutable and therefore be likely to be altered, breaking D's guarantees. It does make me think that it could be valuable to include a comment with the original declaration though (at least in cases where a direct translation isn't possible). That way, it would be clearer that the signature in D isn't quite right. e.g.

/**
    Comment
  */
extern(C) void func(int*const* param);

becomes something like

/**
    Comment
  */
extern(C) void func(int** param);
//orig: void func(int*const* param);

- Jonathan M Davis

> That seems like a good approach, since then you're not marking things as const
> in D that C would consider mutable and therefore be likely to be altered,
> breaking D's guarantees. It does make me think that it could be valuable to
> include a comment with the original declaration though (at least in cases
> where a direct translation isn't possible). That way, it would be clearer that
> the signature in D isn't quite right. e.g.
>
> /**
>      Comment
>    */
> extern(C) void func(int*const* param);
>
> becomes something like
>
> /**
>      Comment
>    */
> extern(C) void func(int** param);
> //orig: void func(int*const* param);
>
> - Jonathan M Davis

That might be a good idea. Thanks for your feedback.

-- 
/Jacob Carlborg