Re: [PATCH] before emit an error message, try to load the babel language

[Ihor Radchenko <yantar92@posteo.net>]

lin Sun <sunlin7@yahoo.com> writes:

> Thanks for the comment.
> If we switch to the `add-variable-watcher', it seems we'll load the
> ob-LANG in the callback immediately.
> The previous change can lazyly load the babel languages until the user
> tries to evaluate the source block.

Is there any advantage doing the loading lazily?
I can only see disadvantages:

1. `setopt' already triggers loading when variable is set. It is just
   `setq', often used in place of `setopt', that does not trigger
   loading/unloading.
2. Lazy loading like you proposed will have to be added in a number of
   places, not just when executing src block: `org-edit-special',
   `org-src-associate-babel-session', `org-edit-src-code',
   `pcomplete/org-mode/block-option/src', org-lint,
   `org-babel-tangle-single-block', `org-babel-exp-src-block',
   `org-babel-exp-results', and others.
3. We will also have to monitor newly added babel functions to take care
   about lazy loading. Not to mention third-party code.

Admittedly, (2) can be solved by abstracting babel backend queries to
API. (I have a WIP code doing exactly this). However, I still see no
good reason to make `setq' different from what `setopt' does now.
Most people treat them interchangeably and then get surprised by the
differences.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
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