Hey Stef,
I think what GNUstep is doing is OK...
On 2013-08-20, at 3:34 PM, Stefan Bidi <[email protected]> wrote:
> I'm re-writing the CoreBase string formatting function (printf with %@
> support) and while going through the printf(), Apple docs and other sources
> on the internet I ran across a potential problem with some of the assumptions
> made when defining these types.
>
> I understand that despite being very portable, GNUstep isn't made to work on
> all platforms, but I'm still going to use an unlikely platform as example...
>
> Anyway, in the Apple docs, they have:
> typedef long NSInteger;
> typedef unsigned long NSUInteger
> typedef long CFIndex;
> Yet, the discussion says:
> When building 32-bit applications, NSInteger is a 32-bit integer. A 64-bit
> application treats NSInteger as a 64-bit integer.
>
> This is true on LP64 platforms but not on any other platform.
It's tricky, because we don't have a definitive specification.
I don't think the "typedef long NSInteger" mentioned in the docs is the
final/proper definition of NSInteger. For example, on OS X 10.8, NSInteger can
be defined as 'int' under some circumstances.
>
> The problem that I see here is that the Apple docs about string formatting
> say that if you want to format a NSInteger/NSUInteger/CFIndex you should use
> '%ld' or '%lu'.
This is from a table in "String Programming Guide", right? I think you may have
missed the "Considerations" column which says to cast the value to a long when
using the %ld format specifier.
This seems to be the accepted interpretation on stackoverflow as well:
http://stackoverflow.com/questions/4405006/nslog-specifier-for-nsinteger
> GNUstep, on the other hand, defines these values as intptr_t/uintptr_t, which
> in my opinion is wrong. We essentially assume these types are as long as a
> pointer, which is true if you assume LP64. However, this assumption is not
> true for a cross-platform library.
> Lastly, I was browsing the web and came across this
> (http://www.nongnu.org/avr-libc/user-manual/group__avr__stdint.html) where
> int is 16-bits, long is 32-bits and intptr_t is 16-bits. I realize AVR is
> not a target, but I just wanted to use it as another example where long is
> not equivalent to intptr_t. And who known, someone might want to use it in
> the future.
>
> I would like to suggest typedef'ing NSInteger/NSUInteger/CFIndex as long.
> That way we can correctly format these integers across all platforms
> supported by GNUstep.
Hope my point addresses your concern.
Cheers,
Eric
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