Re: init.ly, what does it do?

[Thomas Morley]

2017-01-09 4:29 GMT+01:00 David Wright <address@hidden>:
> On Sun 08 Jan 2017 at 21:17:53 (-0500), Br. Samuel Springuel wrote:
>
>> With this file saved to the same folder as my test score,
>> `lilypond-dev --init="my_init.ly" test.ly` produces identical
>> results to `lilypond-dev test.ly`.  I would, therefore, guess that
>> while LilyPond has initialized enough for the code to make sense
>> (i.e. not cause errors the way putting this stuff in an `-e`
>> argument on the command-line does), my_init.ly is still getting
>> executed too early because the settings in it are being overwritten
>> by their default values.
>>
>> So, unless there is a hook somewhere accessible to either `-e` or
>> `--init` that I can use to get the code executed at the right time
>> (i.e. after LilyPond is finished setting the default values but
>> before she actually starts interpreting test.ly), or some way to
>> protect the settings in `my_init.ly` so that LilyPond doesn't/can't
>> change them later, I'm going to have to do something that requires
>> editing the source file before it can be used.
>>
>> Here's hoping someone can prove me wrong.
>
> Well, Simon gave an example where you invoke LP on the
> variable-contents file and include the fixed-contents file.
> Just as easy is to invert this: invoke LP on the fixed-contents file
> (your "source" file) but include a variable-contents file (your
> "my_init.ly" file).
>
> How to do this: just put
> \include "my_init.ly"
> at the start of your source file.
>
> Editing my_init.ly and reinvoking LP on the (unchanged) source file
> will produce a new version of the output using whatever is defined in
> my_init.ly.
>
> You wrote "With separate files, every time I play with the document
> settings, I have to create a new file which has the appropriately
> matched settings and redirect the document to the new file (assuming I
> want to be able to go back to the original settings at some point)."
>
> If you want to preserve previous settings that you've used in
> "my_init.ly" in the past, you can create each my_init.ly in a
> directory whose name is a timestamp like 2017-01-08-20-59-30.¹
>
> Your invocation would use   --include="path/to/2017-01-08-20-59-30"
> to make LP find and insert the appropriate version from that
> directory. Your source would remain unchanged.
>
> Just make sure that you don't put a file called my_init.ly in any
> other directory from which you pick up \include files, ie your
> repositories of LP/scheme code, so that it will only ever be found
> in the timestamped directory.
>
> You also wrote "When borrowing source from other people, however, the
> appropriate Scheme variables won't be there." I don't know what you
> mean by borrowing source. You'd have to explain how you incorporate
> this borrowed code into your projects.
>
> ¹ or any other systematic naming of the directories.
>
> Cheers,
> David.

Samuel,

I'd likely go for --include as David recommended.

Nevertheless, you could store the following lines at top of the ly-file

#(use-modules (guile-user))

#(if (not (defined? 'my-settings))
     (define my-settings '()))

#(for-each
  (lambda (settings)
    (ly:output-def-set-variable! $defaultpaper (car settings) (cdr settings)))
  my-settings)

Then you can call lilypond with
$ lilypond -e='(define my-settings (list (cons (quote indent) 10)(cons
(quote short-indent) 10)(cons (quote line-width) 80)))' file.ly

On windows use double quotes.

Ofcourse you now can use different key-value-pairs in my-settings.
Or even no settings:
$ lilypond file.ly
will still work.

Please note
(1) In terminal spell-out list, cons, quote don't use '-signs
(2) A warning is printed:
WARNING: #f: imported module (guile-user) overrides core binding
`%module-public-interface'
No clue about its severity.


Cheers,
  Harm