Re: Are hyphens no longer required to prefix postevent tweaks?

[David Kastrup]

Trevor Bača <trevorbaca@gmail.com> writes:

> Are hyphens no longer required to prefix postevent tweaks?

They are still required.

> For years I've been writing a hyphen ...
>
>   - \tweak color #red
>   \startTextSpan
>
> ... to tweak text spanners but no hyphen ...
>
>  <c'
>   \tweak color #red
>   d'
>   b'>4
>
> ... to tweak note heads.
>
> As of 2.25.6, the difference between the two forms of \tweak no longer
> appears necessary: globally replacing thousands of "- \tweak ..." with
> just "\tweak ..." now seems to work perfectly.

Don't.

> This change is really great! Trying to divine (and then remember)
> which of dozens of grobs are postevents (versus events?) was a
> pain. And the effort now appears no longer necessary.

Post events from music functions (like \tweak) are now accepted into
music lists (though not necessarily elsewhere).  When a music list is
completed, there is a clean-up sweep attaching lone post events to the
preceding music.  This may be too late and/or the preceding music may be
too complex to attach a post-event to it.  Check for example

{
  \magnifyMusic 2 c'2-\tweak color #red \p
  \magnifyMusic 2 c'2 \tweak color #red \p
}

> Is the change intentional? I must have missed it in CHANGES,

It's a 2.22 change (2.21.0 actually).  You are right that it doesn't
appear in "Changes" in 2.22.  Part of the reason is that it is a patch
more intended to silence the user than LilyPond by attempting a "do what
I mean" on a superset of valid input with a reasonably straightforward
patchup attempt.  The above at least gives off a warning.  But if you,
for example, do

{
  \displayLilyMusic c'2-\tweak color #red \p
  \displayLilyMusic c'2 \tweak color #red \p
}

you get differing results and not even a warning.  Overall, it is an
improvement, but relying on it is a bad idea.

> and the NR entry for \tweak
> <https://lilypond.org/doc/v2.25/Documentation/notation/the-tweak-command#index-_005ctweak-1>
> still shows ...
>
>   \relative { c'-\tweak thickness #5 ( d e f) }  % hyphen
>
> ... even though ...
>
>   \relative { c' \tweak thickness #5 ( d e f) }  % no hyphen
>
> ... works under 2.25.6.

As long as you cannot rely on it working outside of simple cases, it is
not a good idea to advertise it.

> Thanks so much for this!

If you want to check the discussion, this was issue 5181.  It's a
Pyrrhic horse, really.

-- 
David Kastrup