Building identifiers algorithmically
LilyPond Schemers, I'm gradually getting the hang of Scheme, but I'd like some help with one frustrating issue. I'd like to build an identifier from two strings and use it to reference a LilyPond variable. In other words, I have several Lily variables defined like this SopranoMusic = \relative { ... } and I'd like to reference them from Scheme code using the strings "Soprano" and "Music". The only way I've found is to build an alist of all of them using #(set! index (assoc-set! index "SopranoMusic" SopranoMusic)) and then retrieve the music with #(define music (assoc-ref index (string-append "Soprano" "Music"))) (In my real-use case of course some of the strings are variables.) Now while this works it seems rather clunky, so I'm wondering if there is a more elegant way of doing this. Symbols look like they might help, but so far I've failed to make anything work. I've also failed with macros, but that's likely because I don't understand them yet. TIA, Trevor ___ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: Building identifiers algorithmically
Hi Trevor, hey, that's what I just learned :-) What you need is (ly:parser-lookup parser 'SopranoMusic) inside a music function. Then create the 'SopranoMusic symbol from two strings and you're good to go. \version "2.19.18" SopranoMusic = { c' d' } getMusic = #(define-music-function (parser location label1 label2) (string? string?) (ly:parser-lookup parser (string->symbol (string-append label1 label2 \score { \new Staff \getMusic "Soprano" "Music" } HTH Urs Am 21.03.2015 um 23:29 schrieb Trevor Daniels: LilyPond Schemers, I'm gradually getting the hang of Scheme, but I'd like some help with one frustrating issue. I'd like to build an identifier from two strings and use it to reference a LilyPond variable. In other words, I have several Lily variables defined like this SopranoMusic = \relative { ... } and I'd like to reference them from Scheme code using the strings "Soprano" and "Music". The only way I've found is to build an alist of all of them using #(set! index (assoc-set! index "SopranoMusic" SopranoMusic)) and then retrieve the music with #(define music (assoc-ref index (string-append "Soprano" "Music"))) (In my real-use case of course some of the strings are variables.) Now while this works it seems rather clunky, so I'm wondering if there is a more elegant way of doing this. Symbols look like they might help, but so far I've failed to make anything work. I've also failed with macros, but that's likely because I don't understand them yet. TIA, Trevor ___ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel ___ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: Building identifiers algorithmically
Thanks Urs, that what I needed! Trevor - Original Message - From: "Urs Liska" To: Sent: Saturday, March 21, 2015 10:44 PM Subject: Re: Building identifiers algorithmically > Hi Trevor, > > hey, that's what I just learned :-) > > What you need is (ly:parser-lookup parser 'SopranoMusic) inside a music > function. > Then create the 'SopranoMusic symbol from two strings and you're good to go. > > \version "2.19.18" > > SopranoMusic = { > c' d' > } > > > getMusic = > #(define-music-function (parser location label1 label2) >(string? string?) >(ly:parser-lookup parser > (string->symbol > (string-append label1 label2 > > \score { > \new Staff \getMusic "Soprano" "Music" > } > > HTH > Urs > > Am 21.03.2015 um 23:29 schrieb Trevor Daniels: >> LilyPond Schemers, >> >> I'm gradually getting the hang of Scheme, but I'd like some help with one >> frustrating issue. I'd like to build an identifier from two strings and use >> it to reference a LilyPond variable. >> >> In other words, I have several Lily variables defined like this >> >> SopranoMusic = \relative { ... } >> >> and I'd like to reference them from Scheme code using the strings "Soprano" >> and "Music". The only way I've found is to build an alist of all of them >> using >> >> #(set! index (assoc-set! index "SopranoMusic" SopranoMusic)) >> >> and then retrieve the music with >> >> #(define music (assoc-ref index (string-append "Soprano" "Music"))) >> >> (In my real-use case of course some of the strings are variables.) >> >> Now while this works it seems rather clunky, so I'm wondering if there is a >> more elegant way of doing this. Symbols look like they might help, but so >> far I've failed to make anything work. I've also failed with macros, but >> that's likely because I don't understand them yet. >> >> TIA, Trevor >> ___ >> lilypond-devel mailing list >> lilypond-devel@gnu.org >> https://lists.gnu.org/mailman/listinfo/lilypond-devel > > > ___ > lilypond-devel mailing list > lilypond-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/lilypond-devel ___ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel