gtk: Allow user defined overrides

[SpeDAllen]

• allows users to assign colors from theme
• simplifies the gtk mustache

[danth]

This is already possible by writing ${config.lib.stylix.colors.baseXX} within the definition of extraCss, and that can be simplified using with config.lib.stylix.colors; to avoid repetition.

Does having this as a variable within the CSS provide any additional benefits?

[SpeDAllen]

I had not considered using ${config.lib.stylix.colors.baseXX} in the extra css. I did try #{{baseXX-hex}} and #${baseXX} and several other patterns that did not work. I had been using the full hashed value such as #959dcb and wanted a way for the value to change with a theme change. As far as does having the variable in the css provide any benefit. I believe it's more readable. A pattern of lines ending in @baseXX; with baseXX defined in the first few lines is easier to read and understand then a pattern of lines ending in #{{baseXX-hex}}; I guess reasonable people could disagree on such a thing though. I took my inspiration from the resulting css provided by the waybar module. Perhaps I could claim the benefit is consistency.

[danth]

I'm not sure which way to go with this.

On one hand, having variables defined in the CSS makes the output file more readable.

On the other, we could argue that you should be reading the source code and not the generated file. Removing a level of indirection also makes the file smaller and possibly more efficient to load, depending on the details of the parser.

When we make a decision we should update either this or the Waybar module to follow a standard format.

[trueNAHO]

Related: #230

[SpeDAllen]

I guess this opened a bigger can of worms then I expected, my apologies. As someone with much much less experience in this space then you it appears to me that having the variables defined in the CSS would make using stylix more approachable for users less experienced then me. Regardless of what you decide I'd like to assist in standardizing the solution across the modules.

[danth]

No worries, this is something we should try to improve.

Having different methods may actually be more confusing for inexperienced users - they could read @baseXX in a string and assume this works everywhere, then have issues when they try it with a string which doesn't contain CSS. The ${baseXX} method works in all cases (with the appropriate with config.lib.stylix.colors; statement at the top of the file).

[SpeDAllen]

I think I'm missing something. When you say the ${baseXX} method are you referring to using no mustache file similar to the zathura module?

[danth]

Yes, I'm referring to strings written directly within a Nix file, not a separate template.

The current state (ignoring the Waybar module) is that:

• ${baseXX} is used in Nix files
• {{baseXX}} is used in Mustache files

Which has a clear separation of syntax by the different file types.

If we add CSS variables too, it becomes:

• ${baseXX} can be used in Nix files
• {{baseXX}} can used in Mustache files
• @baseXX can be used in either, but only if it's CSS

[SpeDAllen]

Ok, yes, it's taking advantage of a feature of css given the fact that not every product uses css.

If consistency across all the modules is desired and simple user defined overrides are also desired perhaps a third alternative is worth considering. The alternative that springs to mind is converting all color assignments to nix attribute sets. I realize this option would mean a major rewrite to stylix but it would achieve both goals. Unless you expect adoption of stylix outside the context of nixos users should already be familiar with using nix attribute sets and it would align stylix with most home manager modules.

[trueNAHO]

If consistency across all the modules is desired and simple user defined overrides are also desired perhaps a third alternative is worth considering. The alternative that springs to mind is converting all color assignments to nix attribute sets. I realize this option would mean a major rewrite to stylix but it would achieve both goals. Unless you expect adoption of stylix outside the context of nixos users should already be familiar with using nix attribute sets and it would align stylix with most home manager modules.

This would also most likely improve evaluation time: #159 (comment).