Re: A matter of optional arguments

[Jean Abou Samra]

Le 23/12/2022 à 17:54, Rip _Mus a écrit :
> Hello everyone,
> I'm working on a function that prints a personal type of tremolo.
> This function has four arguments, the first and the last are optional.
> The first is actually optional, as you can see in the minimal exemple 
> attached. The last, instead, is problematic: if I omit it, there is an 
> error.
> May I ask for your help?



Trailing optional arguments are simply not supported, as they would mess 
up the parsing. See

https://lilypond.org/doc/v2.24/Documentation/extending/scheme-function-usage.html

If an optional argument is the last argument, the only way to use it is 
to put \default as a placeholder.

You can also most the 'st' argument just after 'fr'. In that case, if 
you want to use it, you have to specify fr with its default 1/4, because 
once an optional argument is skipped, all following optional arguments 
are skipped. (\default would not work, since it also sets all the 
following arguments to their default values.)

Yet another possibility is putting 'st' between 'main-note' and 
'aux-pitch', in which case it will really behave in the most flexible way.

Best,
Jean

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