CSS Modules inspired by ReactJS

[Archmonger]

Current Situation

There is built-in method of directly tying a CSS file to a component

Proposed Actions

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Design Idea: Apply in-line styles via Python cssselect

We could parse the CSS document using lxml.cssselect and potentially add the styles in-line. Would need to generate some sort of VDOM-LXML compatibility layer though. Maybe we store our VDOM as an attribute on each LXML node?

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Design Idea: Apply in-line styles via Python homebrewed VDOM selector engine

It might be make sense (from a performance standpoint) to homebrew a VDOM-compatible CSS selection engine... There are a couple we can take inspiration from: vtree-select, cssauron. This would be a pretty large undertaking, and gets really tricky with all of the CSS level 3 selectors.

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~~Design Idea: Leverage django_css~~

~~Add a css_module decorator that loads a stylesheet using django_css(..., only_once=True) (see here: #194).~~

~~By default, it will attempt to load the Django static file named <REACTPY_STYLESHEET_SUBDIR>/<COMPONENT_DOTTED_PATH>.css. But the user will be able to override the path using positional args.~~

~~Will need a settings.py configuration setting called REACTPY_STYLESHEET_SUBDIR. Additionally, it makes sense for a manual override to exist within the decorator css_module(subdir="...") for library maintainers to use.~~

This doesn't really "tie" a piece of CSS to a component. It only ties the load time together.

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~~Design Idea: Apply in-line styles via JavaScript (client sided)~~

~~It's also possible for us to instead apply the inline styles client-sided, via some kind of JavaScript. There appears to be a package that does this.~~

This would be pretty janky in terms of loading behavior.

[Archmonger]

Blocked on https://github.com/reactive-python/reactpy-django/issues/194

[Archmonger]

Unmarking this as blocked, since a better approach is likely going to involve inline styles.