Re: How to include a file/definition temporarily?

[Carl Sorensen]

On 9/20/10 1:19 AM, "David Kastrup" <address@hidden> wrote:

> Patrick Schmidt <address@hidden> writes:
> 
>> Hi all,
>> 
>> I have several files with definitions of guitar fret diagrams for
>> various chord shapes (e.g. c-shape.ly, a-shape.ly, g-shape.ly, e-
>> shape.ly and d-shape.ly). I can't include all of these files at the
>> same time in the main file as quite a few chord alternatives start on
>> the same pitch. How can I use those definitions only temporarily? I
>> tried this:
>> 
>> cShape = { \include "c-shape.ly" }
>> aShape = { \include "a-shape.ly"  }
>> 
>> music = \chordmode {
>>   \cShape
>>   c1
>>   \aShape
>>   c1
>> }
> 
> Maybe something like
> 
> stdfretboard = #(copy-list fretboard-table)
> \include "c-shape.ly"
> cshapefretboard = #(copy-list fretboard-table)
> #(set! fretboard-table stdfretboard)
> \include "a-shape.ly"
> ashapefretboard = #(copy-list fretboard-table)
> cShape = #(define-music-function ... (set! fretboard-table
>            cshapefretboard)
> aShape = #(define-music-funciton ...
> 
> or similar.  If c-shape/a-shape just add items to the front of
> fretboard-table, you will not even need to copy stuff.  If it is
> something other than a list, you'll need some other copying mechanism.

This is a good thought as a temporary workaround.  However, it won't work
as-is, because fretboard-table is a hash table.  We'd need to define a
hash-table copy function:

(define (hash-table-copy my-table)
  (let ((new-hash-table (make-hash-table 100)))
    (hash-for-each (lambda (key value)
                     (hash-set! new-hash-table key value))
                   my-table)
     new-hash-table))

then replace copy-list above with hash-table-copy.

cShape and aShape would then be defined as void music functions, which is
not shown in David's code above.

Thanks for the idea, David.

Note:  the code above is *not* tested. I hope to get it tested in the next
day or two.

This is still only a temporary workaround, I think, because we should avoid
the hard-coded fretboard-table.

Carl