Re: \set vs \override

[Mats Bengtsson]

David Kastrup wrote:
> > We used to have the same command for setting both context and object
> > properties, see
> > http://lilypond.org/doc/v2.2/Documentation/topdocs/out-www/NEWS.html
> >     
>
> I read
>
>     The syntax for setting properties has been simplified: the following
>     table lists the differences:
>
>                     (old)                           (new)
>
>               \property A.B = #C                \set A.B = #C
>               \property A.B \unset              \unset A.B
>               \property A.B \set #C = #D        \override A.B #C = #D
>               \property A.B \override #C = #D   (removed)
>               \property A.B \revert #C          \revert A.B #C
>      
> There is no differentiation between "context" and "object" properties
> here.
>   
Of course there is! The \property A.B = #C syntax was used for context 
properties (called "translation properties" in the 2.0 documentation) 
whereas the \property A.B {\set,\override} #C = #D was used for object 
properties (called "layout properties" in the 2.0 documentation). See 
for example 
http://lilypond.org/doc/v2.0/Documentation/user/out-www/lilypond/Tuning-output.html#Tuning-output 
which explicitly states that you should not confuse layout properties 
with translation properties. In 
http://lists.gnu.org/archive/html/lilypond-user/2003-10/msg00195.html 
you can find an attempt I did at that time to introduce the different 
kinds of properties and how to set them. I'm still missing this kind of 
overview in the Learning manual, but haven't really had the time to 
write it down.

I share your concerns that there's no clear-cut distinction between what 
is handled by layout properties and and what's handled by context 
properties, but it used to be much worse in old LilyPond versions, where 
we had more context properties that de facto dealt with only one 
particular layout object.


   /Mats

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        Mats Bengtsson
        Signal Processing
        School of Electrical Engineering
        Royal Institute of Technology (KTH)
        SE-100 44  STOCKHOLM
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