Add Jinja2 templating

[fredrik-bakke]

Builds on #6. This PR adds Jinja2 templating support to YAML files. (I think it would also be possible to use it with JSON if you prefer, but I haven't tried this. It should be easy to try to modify the script to try this out.) I use only very simple features of the language, like defining reusable constants, macros, and sometimes to generate code with for loops, but it may have a lot more useful features as well.

[fizruk]

@fredrik-bakke we will be leaving TextMate grammar as a fallback highlighting mechanism. So, if you are willing to update this PR, I think we can merge it.

[fredrik-bakke]

Great! I've resolved the merge conflict now

[fizruk]

I get the following error on my machine:

 *  Executing task: python ./process_jinja_templates.py 

zsh:1: command not found: python

 *  The terminal process "/bin/zsh '-c', 'python ./process_jinja_templates.py'" failed to launch (exit code: 127). 
 *  Terminal will be reused by tasks, press any key to close it. 

Apparently, I don't have python globally (but I have python3). I guess, this is my local problem, but not entirely sure.

@aabounegm can you please check this PR on your machine as well?

[fredrik-bakke]

I just realized I need to change one other thing. Give me a minute.

[fredrik-bakke]

I get the following error on my machine:

 *  Executing task: python ./process_jinja_templates.py 

zsh:1: command not found: python

 *  The terminal process "/bin/zsh '-c', 'python ./process_jinja_templates.py'" failed to launch (exit code: 127). 
 *  Terminal will be reused by tasks, press any key to close it. 

Apparently, I don't have python globally (but I have python3). I guess, this is my local problem, but not entirely sure.

@aabounegm can you please check this PR on your machine as well?

If you're using zsh on Mac, then you can create an alias by adding the line

alias python=python3

to your ~/.zshrc file.

EDIT: Never mind, this turned out to not help in this particular instance.

[fizruk]

I will make a release without this one, as it seems not particularly important. Will make it into the next one. Hope this is okay :)

[fredrik-bakke]

If you're using zsh on Mac, then you can create an alias by adding the line

alias python=python3

to your ~/.zshrc file.

EDIT: Never mind, this turned out to not help in this particular instance.

Turns out you have to add the line to your ~/.zshenv file.

[fredrik-bakke]

I will make a release without this one, as it seems not particularly important. Will make it into the next one. Hope this is okay :)

Sure, no problem! I just figured I could make it ready for merging so that I could work with it in the future.

[aabounegm]

@fizruk It turns out the issue I was having was related to my configuration of PowerShell in VS Code, so I removed the customization and now both shell and process task types work.

[aabounegm]

Hello @fredrik-bakke, sorry for such a late response, but I had forgotten about this PR 😅. To be quite frank, I'm not a big fan of Jinja templating in YAML, I barely even liked it in HTML 😁. I think in this case it could possibly lead to more unreadable config files (judging by some experience writing Helm charts) and I would far prefer using YAML's own anchors (&) and aliases (*) syntax.

Do you have a use case in mind in which Jinja templates would be more readable/useful or can I close this PR?

[fredrik-bakke]

That's completely up to you! I made the PR because it was fast to do so, and I had some success using it in the past. The important thing is to have an element of metaprogramming to make the script consistent and maintainable. You can see how I use it for syntax highlighting for Agda in this file: https://github.com/fredrik-bakke/agda-syntax-vscode/blob/main/syntaxes/agda.tmLanguage.j2.yml

[fredrik-bakke]

In the past I was looking to make some contributions to this extension and I didn't want to do that without having a metaprogramming feature in place.

[aabounegm]

Ok I see your point, but I personally find these macros and variables unreadable (especially when used inside a RegEx!) and would have a hard time maintaining them. For repeated values, we can just use anchors and aliases. Anyways, I don't think there are planned syntax changes in the near future and we already have semantic highlighting in place.

Thanks for the contribution, but I would prefer not to use Jinja templates (if anything, I personally prefer the JS format of config files supported in tools like ESLint and Prettier which allow for high flexibility and even type safety without compromising on readability)