(ediff)Session Groups

Session Groups
**************

   Several major entries of Ediff perform comparison and merging on
directories.  On entering `ediff-directories', `ediff-directories3',
`ediff-merge-directories', `ediff-merge-directories-with-ancestor',
`ediff-directory-revisions', `ediff-merge-directory-revisions', or
`ediff-merge-directory-revisions-with-ancestor', the user is presented
with a Dired-like buffer that lists files common to the directories
involved along with their sizes. (The list of common files can be
further filtered through a regular expression, which the user is
prompted for.) We call this buffer *Session Group Panel* because all
Ediff sessions associated with the listed files will have this buffer
as a common focal point.

   Clicking button 2 or typing `RET' or `v' over a record describing
files invokes Ediff in the appropriate mode on these files. You can
come back to the session group buffer associated with a particular
invocation of Ediff by typing `M' in Ediff control buffer of that
invocation.

   Many commands are available in the session group buffer; some are
applicable only for certain types of work. The relevant commands are
always listed at the top of each session group buffer, so there is no
need to memorize them.

   In directory comparison or merging, a session group panel displays
only the files common to all directories involved. The differences are
kept in a separate buffer and are conveniently displayed by typing `D'
to the corresponding session group panel. Thus, as an added benefit,
Ediff can be used to compare the contents of up to three directories.

   Session records in session group panels are also marked with `+', for
active sessions, and with `-', for finished sessions.

   Sometimes, it is convenient to exclude certain session records from
a group.  Usually this happens when the user doesn't intend to run
Ediff of certain files in the group, and the corresponding session
records just add clutter to the session group buffer. To help alleviate
this problem, the user can type `x' to mark a session as a candidate
for exclusion and `x' to actually hide the marked sessions. There
actions are reversible: with a prefix argument, `h' unmarks the session
under the cursor, and `x' brings the hidden sessions into the view (`x'
doesn't unmark them, though, so the user has to explicitly unmark the
sessions of interest).

   Group sessions also understand the command `m', which marks sessions
for future operations (other than hiding) on a group of sessions. At
present, the only such group-level operation is the creation of a
multi-file patch.

   A multi-file patch is a concatenated output of several runs of the
Unix `diff' command (some versions of `diff' let you create a
multi-file patch in just one run).  In a session group buffer created in
response to `ediff-directories' or `ediff-directory-revisions', the
user can type `P' to create a multi-file patch of marked sessions
(which must be marked using the `m' command).  Ediff then will display
a buffer containing the patch.  In an `ediff-directories' session, it
is enough to just mark the requisite sessions. In
`ediff-directory-revisions' revisions, the marked sessions must also be
active, or else Ediff will refuse to produce a multi-file patch. This is
because, in the latter-style sessions, there are many ways to create
diff output, and it is easier to handle by running Ediff on the inactive
sessions.