Re: [Mlt-devel] const char stuff in mlt++ (possibly mlt)

[Mads B. D. <ma...@ch...>]

mandag 27 Oktober 2008 skrev Dan Dennedy:
> On Sun, Oct 26, 2008 at 2:20 AM, Mads Bondo Dydensborg > OK. Please
> find attached the first try (or step) in removing these for mlt++.
> > If you can agree with the approach, the next step will be to change some
> > const/non-const in mlt.
> >
> > Points of note:
> > - This patch removes all const->non-const warnings in kdenlive when 
calling
> > mlt++
> > - I have only changed interfaces that are used by Kdenlive - so, I have 
sort
> > of only made explicit what the compiler already does
> 
> hmm, I am not content on leaving it inconsistent, but I suppose I can
> take it the rest of the way from your contribution.

The reason I have not changed more is solely because I am afraid to break 
something. When I only change something the compiler complains about, its 
because I am pretty sure that the usage is probably right, and it really only 
is because const was not used in the declaration.

I don't mind changing "all" char * to const char *, that looks like a const 
char * to me, if you think that it is safe to do. Please bear in mind, that I 
have no code that uses the other interfaces in MLT, so I do not know if I 
break code that relies on Mlt.

> 
> > - If kdenlive passes a const char* to a char* param in mlt++, I have 
changed
> > it to const in mlt++
> > - Where mlt++ passes consts to non-consts in mlt, I have used a const_cast 
and
> > static_cast. I will try to get rid of these in the next revision, but I 
have
> > not looked at mlt yet. If I can't get rid of them, I would assume 
something
> > is wrong in the way kdenlive uses the interface.
> 
> Yeah, this is really ugly, where C++ rears its ugly head IMO:
> 
> static_cast<void*>( const_cast<char*>( id ) )
> 
> I realize its "politically correct" as far as C++ is concerned, but
> this is a binding to a C interface, so a C style cast is highly
> justifiable and preferred by me for readability.

I will try to remove all these casts for "full" patch (both mlt and mlt++).
 const_cast and static_cast have the great attribute, that they are 
highly "grep'able" - but I will change to classic C casts for the full patch.

Will work on a new revision soon - done in a couple of days, probably

Regards

Mads

-- 
Mads Bondo Dydensborg.                               ma...@ch...
If you aim the gun at your foot and pull the trigger, it's UNIX's job to 
ensure reliable delivery of the bullet to where you aimed the gun (in
this case, Mr. Foot). 
                               - Terry Lambert, FreeBSD-Hackers mailing list.