Use actual colors

[glebm]

Following up on the internal discussions. Words are cheap, code is gold.

• Use actual colors everywhere, remove unquote stuff.
• Define rgba-tpl function for generating (invalid) CSS templates (literal rgba($var, 0.5)).

[addyosmani]

Thanks for the PR, @glebm. We're going to take some time to review the implementation here and discuss it with the core team. We appreciate you working on this.

[glebm]

Cheers! Reverted the strip-units change as unitless does not do what I thought it did.

[gauntface]

This gets a big thumbs up from me.

[surma]

👍

[Garbee]

This is a BC break for anyone using the Sass in their own build pipeline. Can't merge before 2.x.

[sgomes]

I'm not sure how much of a BC break this is for folks using SASS, actually, @Garbee. If they're relying on the palette variables directly, perhaps (and I'd argue those should be considered private), but it otherwise seems compatible with our previous variable format.

It seems to me that if you're just defining $color-primary and friends, things should still work. I'll run some tests when I get a chance and comment again.

[glebm]

I have looked into making it backward-compatible:

1. The rgba-tpl is already backwards-compatible, but could use a warning like this:

   @if str-index($color, ",") {
       // TODO: remove for 2.0 release.
       @warn "Please change your variables to use colors.
              Using strings is deprecated and will be removed in v2.0.";
   }

2. There are a number of places that previously used unquote("rgb(...", such as:

      .mdl-color-text--deep-purple-A400 {
   -    color: unquote("rgb(#{$palette-deep-purple-A400})") !important;
   +    color: $palette-deep-purple-A400 !important;
      }

   These would require introducting another function such as color-or-string to be backwards-compatible. Let me know if you want this done, or rather postpone for v2.

[Garbee]

This has to be postponed to 2.0. Internally we can update all we want. Other developers however may have included MDL and used the Sass in their pipeline, then used the unquote hack in their code to get the colors. That means it is a breaking change.

[glebm]

No, this can be made backwards-compatible with the unquote hack. Nothing we can do if somebody is using unquote in their codebase, as e.g. rgba(#fff, 0.5) is invalid CSS, so has to go to v2.

[Garbee]

Ok, I'm confused on that one. If someone already has unquote("rgb(#{$palette-red-50})") defined in their Sass, wouldn't that break once RGB values are introduced? I don't see how it wouldn't unless we override unquote somehow.

[sgomes]

Merged with #4167, thanks @glebm and everyone who reviewed this!