Re: Building with GNUstep make on Panther/Tiger

[Peter Bierman]

At 10:25 PM +0200 6/15/05, Andreas Höschler wrote:
> Hi Peter,
>
> > > I find it discouraging that apps aren't binary 
> > > compatible between 10.2, 10.3 and 10.4, 
> > > although I understand why. I guess Apple tries 
> > > to solve this issue with xCode by creating fat 
> > > bundles containing code for all three OS 
> > > versions.
> >
> > You are misinformed.
> >
> > Apps are absolutely binary compatible from 10.2, 10.3, and 10.4!
>
> Thanks for the info!
>
> > Fat binaries are NOT used for different OS 
> > versions, only for different CPU architectures.
> >
> > In addition, in most cases, things built on 
> > 10.4 will also run on OLDER OS versions
>
> What exactly means "most cases" except the 
> obvious API extension reason? Why does code 
> built one Jaguar not work on Tiger properly then?


Anything built on Jaguar should work on Tiger. 
Period. If it doesn't, there's a bug in the OS, 
or the binary was doing something unsupported 
from the beginning. Apple spends an amazing 
amount of effort on "backwards compatibility". 
That's where 10.4 is able to run any binary built 
for 10.2, etc..

MOST things built on Tiger (10.4) will also run 
on Panther (10.3), etc... That's called 
"forwards" compatibility, and it's MUCH harder, 
because it means that 10.2 somehow is able to 
deal with the FUTURE changes in the OS.


Summary:

Backwards compatibility should always work. The 
binary you build today should continue to work 
tomorrow unless you do something unsupported.

Forwards compatibility will usually work, but you 
shouldn't count on it. If you want to create a 
binary using 10.4 tools that will run on 10.2, 
you should use the 10.2 SDK.

-pmb