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mitsuhiko / minijinja

MiniJinja is a powerful but minimal dependency template engine for Rust compatible with Jinja/Jinja2
https://docs.rs/minijinja/
Apache License 2.0
1.67k stars 101 forks source link

async version of `Source::with_loader` #173

Closed breard-r closed 1 year ago

breard-r commented 1 year ago

Hello,

Currently, it's possible to create a source with a dynamic loader using Source::with_loader which accepts a callback function. That's really great but quite impractical to use in async code, therefore I would like to suggest the addition of a similar function that accepts an async callback (Source::with_async_loader maybe?). For example, that would be handy if one would like to fetch the template from a database using an asynchronous method.

mitsuhiko commented 1 year ago

I'm not sure an async function alone would solve it. For this to make sense the engine engine would have to run in a compatible mainloop as well. I think you are probably better off writing this particular stuff sync and block on the async stuff to come back. You can still make the outer part async too by moving the enter rendering into a thread pool if that's necessary.

Generally making this async would require significant changes in the engine and it would invalidate a lot of the assumptions i want to uphold of the engine (mostly that the stack does not go away). The minijinja-stack-ref experiment entirely depends on this.

mitsuhiko commented 1 year ago

I'm closing this as wontfix since the complexity of this is not worth the benefit.