14.6.5 Change Logs and VC

If you use RCS for a program and also maintain a change log file for it (see Change Log), you can generate change log entries automatically from the version control log entries:

C-x v a

Visit the current directory’s change log file and create new entries for versions checked in since the most recent entry in the change log file (vc-update-change-log).

This command works with RCS only; it does not work with SCCS.

For example, suppose the first line of ChangeLog is dated 10 April 1992, and that the only check-in since then was by Nathaniel Bowditch to rcs2log on 8 May 1992 with log text ‘Ignore log messages that start with `#'.’. Then C-x v a visits ChangeLog and inserts text like this:

Fri May  8 21:45:00 1992  Nathaniel Bowditch  (nat@apn.org)

        * rcs2log: Ignore log messages that start with `#'.

You can then edit the new change log entry further as you wish.

Normally, the log entry for file foo is displayed as ‘* foo: text of log entry’. The ‘:’ after foo is omitted if the text of the log entry starts with ‘(functionname): ’. For example, if the log entry for vc.el is ‘(vc-do-command): Check call-process status.’, then the text in ChangeLog looks like this:

Wed May  6 10:53:00 1992  Nathaniel Bowditch  (nat@apn.org)

        * vc.el (vc-do-command): Check call-process status.

When C-x v a adds several change log entries at once, it groups related log entries together if they all are checked in by the same author at nearly the same time. If the log entries for several such files all have the same text, it coalesces them into a single entry. For example, suppose the most recent checkins have the following log entries:

For vc.texinfo:

Fix expansion typos.

For vc.el:

Don't call expand-file-name.

For vc-hooks.el:

Don't call expand-file-name.

They appear like this in ChangeLog:

Wed Apr  1 08:57:59 1992  Nathaniel Bowditch  (nat@apn.org)

        * vc.texinfo: Fix expansion typos.

        * vc.el, vc-hooks.el: Don't call expand-file-name.

Normally, C-x v a separates log entries by a blank line, but you can mark several related log entries to be clumped together (without an intervening blank line) by starting the text of each related log entry with a label of the form ‘{clumpname} ’. The label itself is not copied to ChangeLog. For example, suppose the log entries are:

For vc.texinfo:

{expand} Fix expansion typos.

For vc.el:

{expand} Don't call expand-file-name.

For vc-hooks.el:

{expand} Don't call expand-file-name.

Then the text in ChangeLog looks like this:

Wed Apr  1 08:57:59 1992  Nathaniel Bowditch  (nat@apn.org)

        * vc.texinfo: Fix expansion typos.
        * vc.el, vc-hooks.el: Don't call expand-file-name.

A log entry whose text begins with ‘#’ is not copied to ChangeLog. For example, if you merely fix some misspellings in comments, you can log the change with an entry beginning with ‘#’ to avoid putting such trivia into ChangeLog.