Re: Coda/Segno sign color override not working: LiliyPond 2.24.0

[David Kastrup]

Jean Abou Samra <jean@abou-samra.fr> writes:

> convert-ly only does text substitutions based on patterns that are
> likely to be old syntax that needs to be converted. It cannot
> understand the logic behind Scheme code. In this snippet, it can't
> determine that what is being looked up in the alist is an
> `articulation-type` value. (And it's not a lack of programming
> resources but a theoretical impossibility,
> cf. 
> [https://en.wikipedia.org/wiki/Rice%27s_theorem](https://en.wikipedia.org/wiki/Rice%27s_theorem).)
> Therefore, it is to be expected that Scheme code can require manual
> conversion.

convert-ly uses heuristics.  There is no point in talking about
"theoretical impossibilities" because convert-ly does not claim to be
doing a 100% job.

But that's no excuse for not trying to do a 90% job instead of a 0% job.

Patterns like

("flageolet" .

(acons "flageolet"

(assoc "flageolet"

have some chance at being candidates for conversion.  How bad is the
chance for false positives?  Considering all articulation types,
probably non-trivial.  And false positives probably weigh heavier than
false negatives concerning conversion.  So it may make sense to look for
those patterns only in expressions that also talk about
articulation-type or its associated data structures.

-- 
David Kastrup