Erik Sandberg wrote:
Hi,
I'm a bit frustrated that one have to add a # before strings and numbers, when
calling a music function. This makes it impossible to do implement commands
such as \bar in Scheme, since the argument to \bar has no # before it.
Problems:
a) It increases the size of parser.yy (\bar could otherwise be defined in
ly/*)
b) It makes it impossible to tweak \bar without re-compiling lilypond
c) It can potentially make users confused: It might be hard to remember in
which situations you're supposed to add a # before a parameter to a music
command.
Are there any plans to do anything about this?
One way could be to force the usage of # before all constants, i.e. forbid
string and DIGIT in commands, and use embedded_scm instead. This would be a
very consistent solution, with a more clean grammar as a result, but OTOH
users may get frustrated that we require them to write more characters.
I'm actually more fond of enforcing # everywhere. Having parameters
without # introduces a lot of unnecessary hairiness. For example, 4.0
sometimes is a float, sometimes it is a dotted quarter duration followed
by a zero. # gives us neatly defined semantics at the expense of a
single character. However, being able to drop tokens and rules from the
parser (MUSIC_FUNCTION_x) is also an asset.
Another way is to allow the usage of non-SCM expressions as parameters to
music functions. I did some experiments on parser.yy, in particular I
replaced all embedded_scm parameters with music_function_param, where
music_function_param is defined as identifier_init but with Music, post_event
and number_expression removed.
>
No shift/reduce conflicts were introduced, and it made it possible to write a
clone of \bar as a Scheme function. In addition, it made it possibile to
reduce the number of MUSIC_FUNCTION* tokens to 5.
Why is this not done? May I write a patch?
Why don't you post the patch so we can see the implications?
In general it would be nice to have more genericity in the parser. I
think that if we do separate MUSIC_FUNCTION_PITCH for example, then we
softcode the following rules
- \transposition
- \key
- \transpose
- \relative
--
Han-Wen Nienhuys - [EMAIL PROTECTED] - http://www.xs4all.nl/~hanwen
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