Re: Problem with /accepts

[Thomas Morley]

2017-04-18 10:55 GMT+02:00 David Kastrup <address@hidden>:
> Thomas Morley <address@hidden> writes:
>
>> 2017-04-17 21:08 GMT+02:00 Roman Stawski <address@hidden>:
>>> Hello all
>>>
>>>
>>> I'm coming across a problem with context definitions:
>>>
>>>     \layout {
>>>         \context {
>>>             \name P
>>>             \alias Voice
>>>         }
>>>
>>> This blows up with the error
>>>
>>> Interpreting music...ERROR: In procedure symbol->string:
>>>     ERROR: Wrong type argument in position 1 (expecting symbol): ()
>>>     Exited with return code 1.
>>>
>>> If I comment out the '\accepts' compilation finishes, (but ignores the
>>> context P obviously).
>>
>> From: NR 5.1.6 Defining new contexts
>>
>> "The mechanisms with which contexts communicate are established by declaring
>> the context \type. Within a \layout block, most contexts will be of type
>> Engraver_group.
>> [...]
>> Copying and modifying an existing context definition will also fill in
>> the type."
>>
>>
>> So (see comments):
>>
>>
>> \layout {
>>     %% define "P" from scratch
>>     \context {
>>         \type "Engraver_group"
>>         \name P
>>         \alias Voice
>>         %% put in engravers for what you want
>>         %% otherwise no output
>>     }
>
> Trigger and wording of error message are not overly helpful here.  This
> should likely be caught at an earlier point of time.
>
> --
> David Kastrup

Out of curiosity, could you point me to where the current error is triggered?

I've added some debugging code:

(define (print-book-with parser book process-procedure)
  (let* ((paper (ly:parser-lookup parser '$defaultpaper))
         (layout (ly:parser-lookup parser '$defaultlayout))
         (outfile-name (get-outfile-name parser book)))

  (pretty-print
    (list
          book
          paper
          (map
                (lambda (sym)
                 (cons
                  (ly:context-def-lookup
                     (assoc-get 'P (ly:module->alist
(ly:output-def-scope layout)))
                     sym)
                  sym))
              (list
                'default-child
                'consists
                'description
                'aliases
                'accepts
                'property-ops
                'context-name
                'group-type))
          (assoc-get 'P (ly:module->alist (ly:output-def-scope layout)))
          outfile-name))

    (process-procedure
          book
          paper
          layout
          outfile-name)))

returning:

(#<Book>
 #< Output_def>
 ((() . default-child)
  (() . consists)
  (() . description)
  ((Voice) . aliases)
  (() . accepts)
  (() . property-ops)
  (P . context-name)
  (() . group-type))
 #<Context_def P atest-55.ly:636:5>
 "atest-55")

Though, I don't see symbol->string applied anywhere there.

Cheers,
  Harm