On Tue, Oct 05, 2004 at 05:22:29PM +0200, Pavel Cahyna wrote:
> On Mon, 04 Oct 2004 17:43:41 +0000, Richard Rauch wrote:
> 
> >  * Use "make replace" on key libraries that you know or
> >    suspect will need to be updated.  (Note that this is a
> >    bit dangerous, but lets you get the library updated
> >    without rebuilding everything that it requires.)
> 
> Why is it a bit dangerous? I never saw an explanation.

I don't know what other aspects may lurk in the mechanics of
pkgsrc, but if you are updating a shared library the API may
change.  Some shared libraries (some? ...hm) on UNIX like systems
neither maintain rigorous backwards compatibility nor use the
library versioning scheme properly.

So if the API changes incompatibly but the applications are still
assuming the old API...boom.  The program will start, and may run
for some time, but it may also crash unexpectedly.

This is less likely to happen if the code is recompiled.  (E.g.,
if data structures change in size, recompiling will use the new
headers.)


That is my understanding.

Again, there may be other issues that I'm not aware of.  But I'm
pretty sure that the above is valid and real enough to require
some concern if you are setting up a computer system for others
to use.

-- 
  "I probably don't know what I'm talking about."  http://www.olib.org/~rkr/