Re: Issue 4083: Implement \tagGroup command (issue 137920043 by address@hidden)

[k-ohara5a5a]

The behavior of the old patch seemed better, in the case where someone
does combine a \keepWithTags A.C with A and C from different groups.  In
that case, the user knows about both tag-groups and might be thinking of
them as a unified group, and expect that command to keep music tagged
\tag#'A \tag#'Q, regardless of the group membership of Q.

The rule "\keepWithTag will keep music if any tag matches" has existed
in the past.  That is, these two examples, similar to a pair you put in
the tracker,
 \keepWithTag A.B \tag B.C \new Staff c'^\markup"AB_BC"
 \keepWithTag A.B \tag B { \tag C \new Staff c'^\markup"AB_B_C" }
are treated differently in current master.

The old patch allowed a description that lets us understand the basics
without understanding tagGroups.
\keepWithTag will keep music if any tag matches,
removing music with unmatching tags,
but ignoring tags in a different tagGroup from any of the tags to keep.



https://codereview.appspot.com/137920043/diff/80001/Documentation/notation/input.itely
File Documentation/notation/input.itely (right):

https://codereview.appspot.com/137920043/diff/80001/Documentation/notation/input.itely#newcode2230
Documentation/notation/input.itely:2230: will then be perfectly
equivalent to
This is not quite true, and I think you don't want it to be true, if
there is music
 \tag#'violinI \tag#'violinII \clef french

https://codereview.appspot.com/137920043/