Re: totally confused by versioning system of libtool...

[Bill Northcott]

On 15/05/2005, at 10:06 PM, Peter O'Gorman wrote:
> > Possibly, the last line could equally be:
> > install_name libfoo.2.dylib compatibility_version 3.0.0   
> > current_version 3.2.15
> > That would have the same effect on Darwin, if applied consistently.
>
> The encoded current_version is for informational purposes only,  
> nothing uses it, compatibility_version is used by dyld (darwin's  
> dynamic linker) when loading libraries. It checks that the library  
> version it loaded has a compatibility_version greater than or equal  
> to the one it saw when it was created by the static linker.

The example is interesting. Thanks.   I tried a few more variations  
on the theme.

Compatibility_version works as you say.

However, it still seems to me that current version is not  
irrelevant.  Although it is not checked by dyld, according to the  
Apple docs both library and client can check it at runtime for  
compatibility, presence of features etc.  So it still seems to me  
that it should be meaningful.

Also and more to the point, the compatibility version in the libfoo  
example should still be 3.0.0 not 5.0.0.  Surely   
compatibility_version 5.0.0 implies a libtool version like 4.0.0 or  
6.12.2, rather than 4.15.2?  Or am I still misunderstanding libtool  
version, which was where we came in?

Bill