Issue 4533: Stop the generic \tweak command from working as override

The problem with letting the generic \tweak command work as an override
is that the tweaking of lyric events becomes awkward since plain lyrics
are hard to distinguish from property names.

This renames the combined tweak/override command into \propertyTweak and
changes all callers requiring the combined functionality to call
\propertyTweak (or its Scheme equivalent) rather than \tweak.

The original issue allowing \tweak to act as an override was issue 2929.
The issue allowing tweaks to function in \lyricmode is issue 2543.

diff --git a/ly/music-functions-init.ly b/ly/music-functions-init.ly
index 045262c0498c3cb1b1a42d84a970dda79f181fe0..9af5c885395fffaf5a4b57215d4ba9ad462479ea 100644 (file)
--- a/ly/music-functions-init.ly
+++ b/ly/music-functions-init.ly
@@ -494,7 +494,7 @@ to the preceding note or rest as a post-event with @code{-}.")
                'automatically-numbered (not mark)
                'text (or mark (make-null-markup))
                'footnote-text footnote)))
-     (once (tweak 'footnote-music mus item))))
+     (once (propertyTweak 'footnote-music mus item))))
 
 grace =
 #(def-grace-function startGraceMusic stopGraceMusic
@@ -553,7 +553,7 @@ If @var{item} is a symbol list of form @code{GrobName} or
 @code{Context.GrobName}, the result is an override for the grob name
 specified by it.  If @var{item} is a music expression, the result is
 the same music expression with an appropriate tweak applied to it.")
-   (tweak 'transparent #t item))
+   (propertyTweak 'transparent #t item))
 
 inStaffSegno =
 #(define-music-function () ()
@@ -924,7 +924,7 @@ If @var{item} is a symbol list of form @code{GrobName} or
 @code{Context.GrobName}, the result is an override for the grob name
 specified by it.  If @var{item} is a music expression, the result is
 the same music expression with an appropriate tweak applied to it.")
-   (tweak 'stencil #f item))
+   (propertyTweak 'stencil #f item))
 
 once =
 #(define-music-function (music) (ly:music?)
@@ -932,7 +932,7 @@ once =
 in @var{music}.  This will complain about music with an actual
 duration.  As a special exception, if @var{music} contains
 @samp{tweaks} it will be silently ignored in order to allow for
-@code{\\once \\tweak} to work as both one-time override and proper
+@code{\\once \\propertyTweak} to work as both one-time override and proper
 tweak.")
    (if (not (pair? (ly:music-property music 'tweaks)))
        (for-some-music
@@ -1388,6 +1388,38 @@ Scheme as a substitute for the built-in @code{\\set} command.")
           (car p))
          (make-music 'Music))))
 
+propertyTweak =
+#(define-music-function (prop value item)
+   (symbol-list-or-symbol? scheme? symbol-list-or-music?)
+   (_i "Add a tweak to the following @var{item}, usually music.
+This generally behaves like @code{\\tweak} but will turn into an
+@code{\\override} when @var{item} is a symbol list.
+
+In that case, @var{item} specifies the grob path to override.  This is
+mainly useful when using @code{\\propertyTweak} as as a component for
+building other functions like @code{\\omit}.  It is not the default
+behavior for @code{\\tweak} since many input strings in
+@code{\\lyricmode} can serve equally as music or as symbols which
+causes surprising behavior when tweaking lyrics using the less
+specific semantics of @code{\\propertyTweak}.
+
+@var{prop} can contain additional elements in which case a nested
+property (inside of an alist) is tweaked.")
+   ;; Why not instead make the parser treat strings preferably as
+   ;; music in lyrics mode rather than as symbol?  Because then
+   ;;
+   ;; \tweak text "whatever" mylyrics
+   ;;
+   ;; will try putting a lyric event with text "whatever" in the text
+   ;; property of lyrics.  So we want expressions allowing both
+   ;; strings and lyrics to deliver strings: more complex conversions
+   ;; should only be attempted when the simple uses don't match the
+   ;; given predicate.
+   (if (ly:music? item)
+       (tweak prop value item)
+       (propertyOverride (append item (if (symbol? prop) (list prop) prop))
+                         value)))
+
 propertyUnset =
 #(define-music-function (property-path)
    (symbol-list-or-symbol?)
@@ -1588,7 +1620,7 @@ appropriate tweak applied.")
        (if (>= total-found 2)
            (helper siblings offsets)
            (offset-control-points (car offsets)))))
-   (once (tweak 'control-points shape-curve item)))
+   (once (propertyTweak 'control-points shape-curve item)))
 
 shiftDurations =
 #(define-music-function (dur dots arg)
@@ -1807,10 +1839,10 @@ command without explicit @samp{tuplet-span}, use
        #{ \unset tupletSpannerDuration #}))
 
 tweak =
-#(define-music-function (prop value item)
-   (symbol-list-or-symbol? scheme? symbol-list-or-music?)
-   (_i "Add a tweak to the following @var{item}, usually music.
-Layout objects created by @var{item} get their property @var{prop}
+#(define-music-function (prop value music)
+   (symbol-list-or-symbol? scheme? ly:music?)
+   (_i "Add a tweak to the following @var{music}.
+Layout objects created by @var{music} get their property @var{prop}
 set to @var{value}.  If @var{prop} has the form @samp{Grob.property}, like with
 @example
 \\tweak Accidental.color #red cis'
@@ -1819,71 +1851,61 @@ an indirectly created grob (@samp{Accidental} is caused by
 @samp{NoteHead}) can be tweaked; otherwise only directly created grobs
 are affected.
 
-As a special case, @var{item} may be a symbol list specifying a grob
-path, in which case @code{\\override} is called on it instead of
-creating tweaked music.  This is mainly useful when using
-@code{\\tweak} as as a component for building other functions.
-
-If this use case would call for @code{\\once \\override} rather than a
-plain @code{\\override}, writing @code{\\once \\tweak @dots{}} can be
-convenient.
-
 @var{prop} can contain additional elements in which case a nested
 property (inside of an alist) is tweaked.")
-   (if (ly:music? item)
-       (let ((p (check-grob-path prop (*location*)
-                                 #:start 1
-                                 #:default #t
-                                 #:min 2)))
-         (cond ((not p))
-               ;; p now contains at least two elements.  The first
-               ;; element is #t when no grob has been explicitly
-               ;; specified, otherwise it is a grob name.
-               ((music-is-of-type? item 'context-specification)
-                ;; This is essentially dealing with the case
-                ;; \tweak color #red \tweak font-size #3 NoteHead
-                ;; namely when stacked tweaks end in a symbol list
-                ;; rather than a music expression.
-                ;;
-                ;; We have a tweak here to convert into an override,
-                ;; so we need to know the grob to apply it to.  That's
-                ;; easy if we have a directed tweak, and otherwise we
-                ;; need to find the symbol in the expression itself.
-                (let* ((elt (ly:music-property item 'element))
-                       (seq (if (music-is-of-type? elt 'sequential-music)
-                                elt
-                                (make-sequential-music (list elt))))
-                       (elts (ly:music-property seq 'elements))
-                       (symbol (if (symbol? (car p))
-                                   (car p)
-                                   (and (pair? elts)
-                                        (ly:music-property (car elts)
-                                                           'symbol)))))
-                  (if (symbol? symbol)
-                      (begin
-                        (set! (ly:music-property seq 'elements)
-                              (cons (make-music 'OverrideProperty
-                                                'symbol symbol
-                                                'grob-property-path (cdr p)
-                                                'pop-first #t
-                                                'grob-value value
-                                                'origin (*location*))
-                                    elts))
-                        (set! (ly:music-property item 'element) seq))
-                      (begin
-                        (ly:parser-error (_ "Cannot \\tweak")
-                                         (*location*))
-                        (ly:music-message item (_ "untweakable"))))))
-               (else
-                (set! (ly:music-property item 'tweaks)
-                      (acons (cond ((pair? (cddr p)) p)
-                                   ((symbol? (car p))
-                                    (cons (car p) (cadr p)))
-                                   (else (cadr p)))
-                             value
-                             (ly:music-property item 'tweaks)))))
-         item)
-       (propertyOverride (append item (if (symbol? prop) (list prop) prop)) value)))
+   (let ((p (check-grob-path prop (*location*)
+                             #:start 1
+                             #:default #t
+                             #:min 2)))
+     (cond ((not p))
+           ;; p now contains at least two elements.  The first
+           ;; element is #t when no grob has been explicitly
+           ;; specified, otherwise it is a grob name.
+           ((music-is-of-type? music 'context-specification)
+            ;; This is essentially dealing with the case
+            ;; \tweak color #red \propertyTweak font-size #3 NoteHead
+            ;; namely when stacked tweaks end in a symbol list
+            ;; rather than a music expression.
+            ;;
+            ;; We have a tweak here to convert into an override,
+            ;; so we need to know the grob to apply it to.  That's
+            ;; easy if we have a directed tweak, and otherwise we
+            ;; need to find the symbol in the expression itself.
+            (let* ((elt (ly:music-property music 'element))
+                   (seq (if (music-is-of-type? elt 'sequential-music)
+                            elt
+                            (make-sequential-music (list elt))))
+                   (elts (ly:music-property seq 'elements))
+                   (symbol (if (symbol? (car p))
+                               (car p)
+                               (and (pair? elts)
+                                    (ly:music-property (car elts)
+                                                       'symbol)))))
+              (if (symbol? symbol)
+                  (begin
+                    (set! (ly:music-property seq 'elements)
+                          (cons (make-music 'OverrideProperty
+                                            'symbol symbol
+                                            'grob-property-path (cdr p)
+                                            'pop-first #t
+                                            'grob-value value
+                                            'origin (*location*))
+                                elts))
+                    (set! (ly:music-property music 'element) seq))
+                  (begin
+                    (ly:parser-error (_ "Cannot \\tweak")
+                                     (*location*))
+                    (ly:music-message music (_ "untweakable"))))))
+           (else
+            (set! (ly:music-property music 'tweaks)
+                  (acons (cond ((pair? (cddr p)) p)
+                               ((symbol? (car p))
+                                (cons (car p) (cadr p)))
+                               (else (cadr p)))
+                         value
+                         (ly:music-property music 'tweaks)))))
+     music))
+
 
 undo =
 #(define-music-function (music)