Am Fr., 12. Aug. 2022 um 07:45 Uhr schrieb Andrew Bernard <andrew.bern...@mailbox.org>: > > Although I have long experience in software development, the Lilypond source > is a body of work that I have never really been able to comprehend. This is a > pity as I always wanted to help with development. Now, when I have technical > issues need knowledge of internals, such as my recent effort relating to > noteheads, there is a handful of deeply learned people who come to my > assistance, and I am grateful. What I want to ask today is this. The > solutions seem to pull commands out of thin air with deep understanding, and > I have no idea how to find out this stuff for my self. The internals > reference manual is hardly discursive in nature. So Jean, Valentin, Harm > (still here?), how have you come to acquire this deep knowledge? I don't know > how or where to start.
Yeah, I'm still here :) Though, my real life job became more time consuming, especially during Covid-lockdowns my workload exploaded. Additionally I'm getting older, loosing energy and motivation to work on every problem which arrives. Thus I'm a little less active than I used to be. My own history with LilyPond is similar to Jean's in some regards, different in others. First, I didn't had any programming experience before using LilyPond. No python, no guile, no C++. Being a guitarist, I soon felt the need to extend LilyPond to fit my needs. Notation of classical guitar is one of the most complex ones: Always one Staff with multiple Voices, lots of fingering instructions (Fingering, StrokeFinger, StringNumber, barre, flageolets, etc). Btw, we still don't have a barre-sign which fits everyones needs. Thus I started to learn scheme/guile. At that time only our Extending Manual and several online scheme-tutorials were available. Our Extending Manual is not that bad. It has a short scheme-tutorial. And demonstrates several basic codings for markup-(list-)commands, music-functions and "difficult tweaks". At the time I started scheme/event-functions were not invented, unpure-pure-containers neither, afair. So I started to do some homework: defining lots of custom markup-commands, markup-list-commands and music-functions. It made me familar with basic coding principles in scheme/lilypond. I joined the german lilypond forum to get help where my so far accumulated knowledge ended. Soon I joined this mailing-list to get even more help. In return to that help I tried to answer questions from other users. For some time I actually looked at every user-request, at least compiling the problem and posting an answer, if I found one. This increased my knowledge enormously. I think, working on user-requests on the mailing-list can't be over-estimated regarding one's own insights. Having done a LSR (ofcourse with help from others) increased it even more. Looking/analysing/playing-around at/with posted code from other big coders like (at that time) Mike Solomon, David Nalesnik, David Kastrup and several others were another big step forward as well. Soon I wished to get some of my custom solutions into the source, so I learned how to do so. Dealing with git, regression-tests, the patch-upload/approving cycle, etc. Nowadays, all became a little easier. We have Jean's great https://extending-lilypond.readthedocs.io. And our own docs became better. For development we use GitLab. Nevertheless I still don't know python and C++. Especially the lack of C++-knowledge[*] sometimes hinders me to get to real and general working solutions for certain problems, p.e. if I need to look at several different grobs to set a certain behaviour of the original overriden grob and the needed-to-know properties of those other grobs are done as unpure-pure-containers. Furthermore I quite frequently need to experiment with things because I am not able to deduce behaviour from the C++ source. Thus I often need a code-example. Not saying I need to copy, but to know we have a page-post-process hook does not enable me to use it. Reading the example in Usage Manual is what I needed to became familar with it. (Btw, there is a recent coding by Jean using it, posted here on the list.) > So much of my modernist work needs internals knowledge, and even though I > have built up a large library of extension code in Lilypond and Scheme, I am > still all at sea. > > Any advice? I know Scheme and C++ very well. It's the functions and what they > do that I don't understand enough. Here's an example. > > LY_DEFINE (ly_stencil_outline, "ly:stencil-outline", > 2, 0, 0, (SCM stil, SCM outline), > R"( > Return a stencil with the stencil expression (inking) of stencil @var{stil} > but > with outline and dimensions from stencil @var{outline}. > > I can understand what dimensions means but what is the 'outline' of a > stencil, and how is it used? Just one example of my profound ignorance. > > > Andrew As I wrote, I often make experiments. Here I'd start with \markup \overlay { \stencil #(stencil-with-color (make-filled-box-stencil '(0 . 10) '(0 . 10)) red) \whiteout \stencil #(ly:stencil-outline (stencil-with-color (make-filled-box-stencil '(0 . 5) '(0 . 5)) cyan) (make-filled-box-stencil '(0 . 8) '(0 . 8))) } Probably continuing by researching for stencil-true-extent. Alas, skylines are not scheme accessible afaik. Ofcourse show-horizontal/vertical-skylines will help. as Jean wrote, though that was not invented a few years back. As sort of a summary, I'd like to emphasize that the work on user requests on the mailing-list is the most promising part to get more insight in LilyPond internals. Ofcourse reading the source-code is another very important part, even if (as in my case) resticted to scm-files. Third thing: understanding other posters coding. Best, Harm [*] A short story about my attempt to learn C++ Years ago I felt it would be nice to know C++, thus I took some online tutorial and started. First there were general explanations and an introduction, then the chapter about a first program, hello-world.cc, started: Do this ... Do that ... Ok, you're ready. Call the program! ??? How??? ??? It was _not_ explained _how_ to call the program. Actually I had to ask an experienced programmer. This made me feel stupid and dump. In the end I felt really pissed. If that state is reached, it will last for years, actually more than decade now, iirc. The good advice "take another tutorial" _is_ good, but I will not follow it. Ask again in another decade or better two.
