Re: [libobjc] May I tweak objc-api.h?

[Mike Stump <mrs at apple dot com>]

On Friday, February 6, 2004, at 02:02  PM, Alexander Malmberg wrote:
> Ziemowit Laski wrote:
> >    typedef struct objc_super {
> >      id      self;                           /* Id of the object 
> > sending
> >                                                  the message. */
> >      Class class;                              /* Object's super 
> > class.
> > */
> >    } Super, *Super_t;
> [snip]
> > So, do you think it would be OK to rename 'class' above to, say,
> > 'super_class'?
>
> This field is used in GNUstep. What do you propose that code should do
> to work with both versions? Change the name only if __cplusplus is
> defined?

There is excellent prior art here, with exactly this issue.  The case 
came up with X11 and C++ and a keyword, probably class, and in some 
area that did affect api code.

The solution they took, was to migrate to a new name, the same new 
name, in C and C++, I think we should do the same.

Something like:

struct A {
	int class;
};

became:

struct A {
	int super_class;
};

and they took the API hit.

For user code, they can do:

#if (__GNUC_ == 3 && __GNUC_MINOR__ < 4)
#define super_class class
#

and then use super_class everywhere.  It compiles on both, and it easy 
to maintain, as long as one doesn't get hit with other things called 
super_class. :-(

The change breaks all user code that uses class, but sometimes an easy 
to describe system is easier to fix than an insanely complex one.

The X11 folks grappled with this, gosh, a long long time ago.  Time to 
enter the 90s.  :-)