Caching cannot and must not be done at this level, because it can be desired to get different connections.
As an example, in MySQL transaction information is local to a connection. So returning an existing connection is not always the same as creating a new one, and only the class doing the actual connection knows what can be shared and what cannot.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27219 20353a03-c40f-0410-a6d1-a30d3c3de9de