Re: ABI Compatibility (was Re: Installation woes for the average user...)

[Wolfgang Lux]

Richard Frith-Macdonald wrote:

> Chasing MacOS-X is a problem for us .. sometimes Apple make changes  
> which require ABI changes.  Often they add new stuff, which we try  
> to add too.  If we don't get the additions quite right in one  
> release, we need to fix them in the next release, and that fix may  
> change the ABI with respect to the new feature, even though the ABI  
> of the main part of the library is stable/unaffected.  This can be  
> something as trivial as implementing an obscure method with an  
> argument of the wrong type (eg a long rather than an int), then  
> having to change the argument type in a later release to match  
> MacOS-X.

I find it quite funny that you regularly bring up Mac OS X  
compatibility as a reason for ABI breakage. Have you ever looked at  
what Apple is doing? I can use executables compiled on Mac OS X 10.2  
on Mac OS X 10.5 without any problems and Mac OS X does ship with  
only a single instance of all its libraries/frameworks. I.e., it was  
possible for Apple to keep the ABI stable and avoid any soname  
changes for all major libraries since at least 10.2. For sure, they  
play some tricks here and check at runtime whether an executable was  
linked against the 10.2, 10.3, 10.4, or 10.5 frameworks and adapt the  
behavior of some methods accordingly.

Wolfgang