CVS update when finding files

[F. Xavier Noria]

Before I start to edit a file that belongs to a project I should C-x v v
to see if it is up to date but my memory is not that reliable, so I
would like to add a function to the find-file-hooks that did the
following

   if the asked file belongs to some repository then
      if it is not up to date then
         ask the user to update the working copy

That sounds short but I am not familiar with Version Control... could
someone be so kind to send some code?

Regards from Barcelona,

-- Xavier