Question

I am thinking of writing a PHP extension library that will use the memcached library. It is trivial to simply link my library to the memcache shlib.

However, I am not sure what will happen if my (extension library) user already uses memcache on his/her website. My questions are:

1. Is it possible to have (possibly different versions) of memcache on the machine?
2. Is it best to statically link or dynamically link to memcache when building the extension library? (to cater for version incompatibilities – assuming memcache is backward compatible, otherwise all bets are off)

The questions basically degenerate to how may one safeguard an extension library they have written if it has a dependence on a third party file which may already be being used on the website that the extension library is going to be used on?

The question may probably be slightly ill-posed, but I hope you understand the gist of what I am asking.

Answer 1

Mind that there are two memcache extensions for PHP, one is called memcache, the other memcached, the first uses it’s own implementation of the memcache protocol, the later uses the library.

If you’re using the first you shouldn’t have a conflcit but have to take care of memcache on your own. I’d suggest building an extension which depends on the memcached and re uses the library it found.