On Mon, 2019-11-04 at 23:45 +0000, Urs Liska wrote:
Dear Urs;
many thanks for your comments and hints! I admire how thoroughly you read other
work and how many time you spend with helping others!
> Hi Karsten,
>
> 4. November 2019 17:59, "Karsten Reincke" <[email protected]> schrieb:
> [...]
> > Here is a pure scheme / guile solution using lisp association lists (demoed
> > by
> > using the box example from the extend tutorial).
>
> I see one major issue with your approach: it pollutes the namespace with a
> multitude of global variables.
The global variables are only syntactical sugar. I've attached a version which
does not use any global variable any longer
>
> I don't want to push you towards using openLilyLib ;-) but oll-core includes a
> macro "with-options" (created by Stéfano Troncaro) that allows the
> modification
> of define-music-function (I'm not sure about markup functions right now) so
> that
> the function accepts an optional \with { } clause, performs validation against
> mandatory and optional arguments (optionally along with their types) and can
> provide default values - all without necessarily using #(define XXX) and
> creating global variables.
>
> The code starts here:
> https://github.com/openlilylib/oll-core/blob/master/internal/options.ily#L245
>
This is a nice example using the main feature of LISP: even code can become a
parameter and vice versa. But for my purpose, it is too sophisticated.
> Urs
wit best regards
Karsten
--
Karsten Reincke /\/\ (+49|0) 170 / 927 78 57
Im Braungeröll 31 >oo< mailto:[email protected]
60431 Frankfurt a.M. \/ http://www.fodina.de/kr/
\version "2.18.2"
% A pure scheme / guile solution to define a LilyPond markup
% command with a variable list of arguments by using a
% technique of lisp scheme / guile called association lists
% (demoed by using the box example from the extend tutorial).
% The target is, that the users of the function may insert
% the arguments they really need (without having to deal with
% those, they do not need) and that they may insert the arguments
% they want to use in the order they prefer
% feel free to adopt this example under the following terms:
% Copyright 2019 Karsten Reincke, Frankfurt
% Permission is hereby granted, free of charge, to any person
% obtaining a copy of this software and associated documentation
% files (the "Software"), to deal in the Software without
% restriction, including without limitation the rights to use,
% copy, modify, merge, publish, distribute, sublicense, and/or sell
% copies of the Software, and to permit persons to whom the
% Software is furnished to do so, subject to the following conditions:
% The above copyright notice and this permission notice shall be
% included in all copies or substantial portions of the Software.
% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
% EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
% OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
% NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
% HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
% WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
% FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
% OR OTHER DEALINGS IN THE SOFTWARE.
% 1) we need a function - let us name it "assign"
% (you will understand in a short time, why) - which takes
% a key, an association list (alist) and a default value.
% If the alist contains any pair with the same key,
% then function shall return the corresponding value,
% otherwise the given default value
#(define (assign keyValue assocList defaultValue)
(let* ((localPair (assoc keyValue assocList)))
(if localPair (cdr localPair) defaultValue)
)
)
% 2.) we define a markup function using a flexible variable
% parameter list:
% a) At the beginning we define the local parameter variables
% and let them be instantiated by our assign function.
% b) Then we manipulate the given values in any way.
% c) And finally we return - as a markup 'object' -
% a box containing the result of our manipulation:
#(define-markup-command (mybox layout props AL)
(list?)
(let*
( (la (assign "k1" AL "blank"))
(lb (assign "k2" AL ""))
(lc (assign "k3" AL '()))
(ld (assign "k4" AL "blank"))
(le (assign "k5" AL ""))
(lresult "result")
)
; because we used an empty list (nil) as default value
(if (eq? lc '()) (set! lc ""))
; our 'manupilation' is a concatenation ;-)
(set! lresult (string-append la lb lc ld le))
(interpret-markup layout props
#{
\markup \box { #lresult }
#}
)
)
)
\markup \mybox #'(("k5" . "V5")("k1" . "V1"))
