The compare menu normally allows you to compare with local history (Eclipse's own version of saved files during a session),
or to compare two selected resources.
However, once a project is connected to a repository, a few new entries are present in the Compare menu:
- Compare With > Base Revision - this will compare the selected resource with the "pristine" version hidden away in the
project's working copy. This happens without contacting the repository.
- Compare With > Latest From Repository - this will compare the selected resource with the latest version
of this resource at the same location in the repository. This requires a lookup to see what the latest version is.
- Compare With > Revision... - this will bring up a dialog showing the change history for the file. You can then easily
compare the file against any previous revision from the repository.
- Compare With > Branch/Tag... - This option allows you to compare your working copy with another URL from the
repository, presumably a different branch/tag of the same project. You are given the option of viewing the output in the
Eclipse graphical compare engine, or using the SVN command to produce a unified diff. The latter operation generally
runs a lot faster and is able to factor out differences in keywords. Of course the graphical compare is a nicer way to view
the differences.
These comparisons are very useful for reviewing the contents of you changes before you commit them.