Hello, Here is an org document setting out my question. It should export cleanly to HTML, without any dependencies other than Jujutsu.
#+title: Noweb source/result evaluation order #+OPTIONS: toc:nil creator:nil author:nil timestamp:nil num:t validate:nil **Warning**: the code below executes =rm /tmp/time-travel-wtf/ -rf=. Make a Jujutsu (=jj=) repository that looks like this #+begin_src sh :eval export :exports results :results output code rm /tmp/time-travel-wtf/ -rf mkdir /tmp/time-travel-wtf jj git init --colocate /tmp/time-travel-wtf/branching cd /tmp/time-travel-wtf/branching jj config set --repo user.name "Your Name" jj config set --repo user.email "y...@example.com" echo 1 >> numbers jj commit -m "Base commit" echo 2 >> numbers jj commit -m "Right commit" jj new -m "Left commit" -r @-- echo 3 >> numbers jj new jj #+end_src We can identify the unique prefix of the head on the non-current branch with: #+name: other-head #+begin_src sh :eval export :exports both :dir /tmp/time-travel-wtf/branching jj log -r 'visible_heads() ~ @' -T 'change_id.shortest()' --no-graph #+end_src #+results: other-head We want to demonstrate how to use this ID to switch branch with =jj new <ID>=. We use noweb to generate the code containing the =jj= instruction containing the specific ID, and add some noise (=echo A=) to help us visually link input to corresponding output. First we only export the code, we do not execute it, so there is no output anywhere containing the =A= marker #+begin_src sh :noweb yes :exports code :dir /tmp/time-travel-wtf/branching echo A <<other-head()>> jj new <<other-head()>> echo A <<other-head()>> #+end_src So far so good. Now we repeat the block with two small variations: 1. Replace the =A= marker with =B= 2. Execute the code and render its output. This time there should be some output containing the =B= marker. #+begin_src sh :noweb yes :exports both :results output code :dir /tmp/time-travel-wtf/branching echo B <<other-head()>> jj new <<other-head()>> echo B <<other-head()>> #+end_src Observations: 1. The code contains =echo B <ID of LEFT branch>= but the output shows =B <id of RIGHT branch>=: the output does not match literal constants printed by the source! 2. The side-effect of the =jj new ...= line seems to take place before that line is constructed. By using a simpler example (one which increments a counter stored in a file), I have discovered that =other-head()= is executed 9 (nine) times: + the first three times (I guess) when rendering the =echo A= source block + three more times when rendering the **result** of the =echo B= block + a further three times when rendering the *source* of =echo B= block. Yes, the occurrences of =other_head()= in the rendering of the source evaluate *after* the occurrences in the rendering of that source code's result! This unexpected order (cause being rendered after effect) would explain the mismatch between the IDs shown in the =echo B= source code and its result. How can we work around this behaviour, in order to 1. render a code snippet containing a specific, *literal* =jj= change ID, 2. execute that code for its side effect, 3. render the output of that code ?
