Re: make-connected-path-stencil with variables and connected paths

[Paul Morris]

David Kastrup wrote
> Thomas Morley <

> thomasmorley65@

> > writes:
> 
>> Hi Paul,
>>
>> 2013/10/20 Paul Morris <

> paul@

> >:
>>> Hi all,  I'm trying to use make-connected-path-stencil, but it's not
>>> working as expected, in two ways.  Here's a tiny example:
>>>
>>> %%%%%%%%%%%%
>>>
>>> \version "2.17.28"
>>>
>>> myStencil =
>>> #(let* ((A 0) (B 1))
>>>    (make-connected-path-stencil
>>>     '((A B) (B B) (A A)) ;; <-- variables can't be used in pointlist?
>>>     0.1
>>>     1
>>>     1
>>>     #f ;; <-- error when connect is set to #t
>>>     #t))
>>>
>>> %%%%%%%%%%%%
>>>
>>> 1. Using variables in the pointlist gives this GUILE error:
>>> Wrong type: A
>>
>> you have to ensure that the elements of the list are evaluated.
>> Look at the different output from:
>>
>> #(let* ((A 0) (B 1))
>>  (display `((,A ,B)(,B ,B)(,A ,A))))
>>
>> #(let* ((A 0) (B 1))
>>  (display '((A B)(B B)(A A))))
>>
>> David explained this recently far better than I could, can't find it
>> at the moment, though,
> 
> Probably
> &lt;URL:http://lists.gnu.org/archive/html/lilypond-user/2013-10/msg00522.html&gt;

Aha!  Thank you Harm and David!  That perfectly explains what I was missing,
and how to make it work.

For anyone else who's interested, I looked this up in the GUILE manual, just
to make sure I understood the difference between using ' and ` and , (quote,
quasiquote, and unquote):
https://www.gnu.org/software/guile/manual/guile.html#Expression-Syntax

I see there's no snippet about using make-connected-path-stencil in the LSR. 
I'll put it on my list to add one when I get a chance.

Thanks again for your help,
-Paul




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