Re: @property problem
Re: @property problem
- Subject: Re: @property problem
- From: Bill Bumgarner <email@hidden>
- Date: Sun, 17 Feb 2008 09:11:37 -0800
On Feb 17, 2008, at 8:59 AM, William Squires wrote:
But it doesn't answer the question. Why even make the change in the
64-bit runtime? This would seem to hide a source of bugs, by taking
the responsibility for providing storage away from the programmer.
Some storage is still necessary. And besides, in order to take
advantage of Leopard features like this one (whether on PPC or
Intel), you should still have to link against the 10.5 SDK, so it
would seem more reasonable to make the update to both the 32 and 64-
bit runtimes, but only in the 10.5 SDK. Then you could update the
10.5 SDK (to 10.5.1) to allow for this "syntactic sugar" under both
32- and 64-bit.
I mean, after all, all it means is that you're changing the default
size of an (Integer) register in the CPU chip, and updating the OS
to take advantage. How would this make implementing (or not
implementing) this change any harder or easier?
Apple does not ship the Tiger version of the frameworks and runtime
with Leopard. All of the frameworks/dylibs on Leopard, while they
contain Leopard specific features, maintain backwards compatibility
with prior releases of the OS.
The changes required to support the various Modern Runtime features
found in the 64 bit version of the Leopard runtime would have required
ABI changes -- changes to the way the compiler generates code, call
sites and/or metadata -- to support. That is, it isn't just
syntactic sugar -- it changes the way Objective-C classes are
represented both in the executable and in memory.
Making a change to the ABI would break all applications that were
compiled for the old ABI.
Or it would require that Apple ship two entire copies of all
frameworks/dylibs on the system; one compiled with the 10.5 ABI and
one compiled with the 10.4-and-prior ABI.
b.bum
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