Re: [Devel] Moving the location of "lsb_delta" and "rsb_delta"

[Owen Taylor]

On Sun, 2004-06-13 at 19:59, Keith Packard wrote:
> Around 9 o'clock on Jun 11, Werner LEMBERG wrote:
> 
> > I thought we've come to the conclusion that the next major FreeType
> > release (2.2) need not be binary compatible with older versions. 
> 
> As long as you change the .so major version number, binary incompatibility 
> is acceptable given sufficient cause.  The only real trouble comes when 
> the binary compatibilty assurances provided by the .so verison numbers 
> aren't actually respected in the library interface.

From a distribution point of view, while the above is true, it
takes a pretty big value of "sufficient cause" ... a binary 
incompatible version means that a distributor has to:

 -  Create and maintain a "compatibility package" for the old
    binary version for the forseeable future.

or:

 - Declare a red-letter day where all applications linking against
   FreeType have to be immediately relinked. (Some 30-40 packages
   distributed with Fedora Core, and an unknown number of 3rd
   party packages)

My feeling is that there basically never a good reason to make a
binary-incompatible change to a library except for a major
rewrite that is also source-incompatible. 

If a library's data types are poorly designed (e.g., stack-allocated
structures that need to be extended) then there may be more of a reason 
for binary-incompatible changes, but I don't see this as being a
problem for FreeType.

Regards,
                                        Owen

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