Hi Riccardo,
On Nov 13, 2017, at 5:24 AM, David Chisnall wrote:
On 13 Nov 2017, at 08:17, Wolfgang Lux <[email protected]> wrote:
While sel_isEqual is just an alias for == on Apple's runtime (and
the GNUstep runtime, I assume), this need not be the case for other
runtimes. In particular, for the old GNU runtime sel_isEqual is not
equivalent to ==, as you've observed.
It’s also not == on the GNUstep runtime, and can’t easily be with a
new ABI if we want it to work on ELF / COFF platforms. Apple relies
on the run-time linker deduplicating their selector table and
inserting selectors into a contiguous region of memory.
Note that Apple didn't add sel_IsEqual() to its runtime until OS X
10.5; If you still want Graphos to support OS X 10.4 & earlier, you'll
need to keep using '==' on Macs. One way to do this without #ifdefs
around each selector comparison would be to use a macro:
#ifdef __APPLE__
# define macroSelectorsAreEqual(selector1, selector2) (selector1 ==
selector2)
#else // GNUstep
# define macroSelectorsAreEqual(selector1, selector2)
sel_isEqual(selector1, selector2)
#endif
...
if (macroSelectorsAreEqual(action, @selector(copy:))) {...
(It's probably safe to assume Apple's runtime will continue
supporting '==' for selector comparison, otherwise it would break a
significant amount of legacy code).
Cheers,
Josh
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