When there have been many changes to the repository, picking exactly which ones
to record can be disorienting. Using a --filter=REGEX tag, one could reduce the
list of changes offered for recording.

A use case:
Sometimes I make many unrelated changes to a file. Then I decide to rename a
variable name (which appears in several places) and record only those changes.

salty-horse,

Thanks for providing feedback on darcs. 

Your "use case" or renaming a variable is what the "darcs replace" command is
for. Since I can't think of any other case where the "filter" option would make
sense, I'm marking this as "won't fix" for now.

If you feel strongly the feature should be added, you could discuss it on the
darcs-users list to try to drum up support, or consider preparing some tests and
code yourself to implement it. 

So far, the "wish" was open for over a year without anyone adding a "me too"
comment to it.