What are the differences between templates and template aliases?

[glehmann]

Hi!

Jujutsu config has [templates] and [template-aliases] tables, but I'm not sure why.
Could someone explain what are differences between them, or point me to a doc that does?

Thanks!

[yuja]

This PR has a better doc.
https://github.com/jj-vcs/jj/pull/5375/files#diff-469111461db0afeadd6194653fc1af2572724bda0d87058d109bf45144d2eb8a

[jennings]

Oof, I need to find the time to rebase that...

[glehmann]

I'm afraid I still can't find the difference between [templates] and [template-aliases], even after looking at that PR :-/

[yuja]

[template-aliases] is a free-form table in which user can define arbitrary aliases as they want. [templates] contains the defaults for a certain commands (e.g. templates.log.)

[CGamesPlay]

I'm experimenting with jj and also found this confusing. It caused me issues when I wanted to override templates.log as many sources on the internet do, but wanted to modify builtin_log_oneline. I copied the built-in definition and modified it, but it didn't work, because I put it in templates instead of template-aliases.

Templates	Template Aliases	Thing
✅	✅	Values are templates
✅	✅	Keys can be simple identifiers
❌	✅	Keys can be functions
❌	✅	Values may be referenced by other templates
❌	✅	Values may be referenced by -T arguments
✅	❌	Values may be referenced by commands without -T

It might be worth revisiting if these things need to be separate config sections. It would perhaps be less confusing if the built-in config exclusively used simple alias lookups as its built-in templates. Revsets appear to have this same seemingly arbitrary distinction, as well.