Re: hash/backslash confusion

[Carl Sorensen]

On 8/13/09 10:37 AM, "Mark Polesky" <address@hidden> wrote:

> Carl Sorensen wrote:
> 
>> Hope this helps.  It was instructional to me to write it.
> 
> Wow, thanks - that was a lot of info. I'm still trying to wrap my
> brain around it. But in the meantime, I've noticed something else
> confusing, and I'm wondering if you'd like to make any additional
> comments on this.

This is *exactly* the same issue.

Anything beginning with \ is a LilyPond string, and can only be alphabetic.
That's the rules for LilyPond.

Anything beginning with # is a Scheme expression, and follows the rules of
Scheme.

\applyOutput takes as its second argument a procedure, which is a scheme
expression.

\blanker is LilyPond parser input for a LilyPond string that evaluates to
the scheme expression blanker, which has a value of (lambda ...)

#blanker is LilyPond parser input for the scheme expression blanker

\blanker-2 won't work, because blanker-2 is *not* a valid LilyPond string.
#blanker-2 will work, because blanker-2 is a valid Scheme expression.

There is no \ string that can work with blanker-2.  When Scheme names
contain numbers or -, the only way to get to them in LilyPond input is via
#, and this can only come in constructs where the parser will accept a
Scheme input, not where a string is needed.

HTH,

Carl


> 
> I'm trying to figure it out, but it's still confusing. Any
> elucidation would be helpful.
> - Mark
> 
> \version "2.13.4"
> 
> %% procedure can be defined with "=" or scheme-style, and
> %% scheme-defined procedure names can have non-alphabetic characters.
> 
> blanker =
> #(lambda (grob grob-origin context)
>    (if (and (memq 'note-head-interface (ly:grob-interfaces grob))
>             (eq? (ly:grob-property grob 'staff-position) 0))
>        (set! (ly:grob-property grob 'transparent) #t)))
> 
> #(define (blankerB grob grob-origin context)
>    (if (and (memq 'note-head-interface (ly:grob-interfaces grob))
>             (eq? (ly:grob-property grob 'staff-position) 0))
>        (set! (ly:grob-property grob 'transparent) #t)))
>       
> #(define (blanker-2 grob grob-origin context)
>    (if (and (memq 'note-head-interface (ly:grob-interfaces grob))
>             (eq? (ly:grob-property grob 'staff-position) 0))
>        (set! (ly:grob-property grob 'transparent) #t)))
> 
> % procedures can be dereferenced with either "#" or "\", but procedure
> % names with non-alphabetic characters can only use "#".
> 
> \relative { e4 g8 \applyOutput #'Voice #blanker b d2 }
> \relative { e4 g8 \applyOutput #'Voice \blanker b d2 }
> \relative { e4 g8 \applyOutput #'Voice #blankerB b d2 }
> \relative { e4 g8 \applyOutput #'Voice \blankerB b d2 }
> \relative { e4 g8 \applyOutput #'Voice #blanker-2 b d2 }
> 
> % this won't work
> % \relative { e4 g8 \applyOutput #'Voice \blanker-2 b d2 }
> 
> 
>