Re: [Bug-gnulib] Patch proposal: 1-gary-safe-xfree.patch

[Gary V. Vaughan]

Paul Eggert wrote:
> "Gary V.Vaughan" <address@hidden> writes:
> > I'd also like an equivalent xfree (in xfree.c) so I can:
> >
> >     lt_dlfree    = xfree;
>
> The patch I most recently proposed allows that, since you can assign
> the address of an inline function to a variable.  You might get
> different function addresses in different modules, but I assume that's
> OK here.

Agreed.  I imagine that it would be rare indeed, even in the case of 
registering cleanup handlers throughout client code, to need to compare the 
addresses of such function pointers.  Your patch definitely suits me :-)

> > how else to prototype the function without polluting xalloc.h?
>
> I think xalloc.h is the natural place for this, so it's not pollution.

I meant in my patch, where xfree was a separate module.  Your solution is 
better.

> > Anyway, how's this?
>
>
> +# define DELETE(Var)   \
> +   do {                        \
> +      XFREE (Var);     \
> +      Var = 0;         \
> +   } while (0)
>
> This has the problem of evaluating Var twice

I don't think that matters, as long as clients are aware of the convention 
that function like macros (with uppercase symbol names) may evaluate arguments 
multiple times: A common style of C programming.

However, it is easy to fix if that is important.  Either way, I think DELETE 
is a nice complement to NEW, but would be delighted to see your latest xfree 
patch applied with or without :-)

> As I get older, I prefer functions to macros more and more.

If you can assume C89, static inline functions are definitely better than 
preprocessor macros.  My coding style has avoided side effects in uppercase 
macro parameters for so long that I'm hardly aware of my doing it now.

Cheers,
        Gary.
--
  ())_.  Gary V. Vaughan    gary@(lilith.warpmail.net|gnu.org)
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