Scss mixin function variable scope

Question

Not shure if this is a scope issue, well consider the following:

$custom : #f20;

@mixin colorbyclass($class) {
  .#{$class} {
    background: $class;
  }
}

//scss
@include colorbyclass(custom);

//compiles
.custom { color:custom; }

My issue being that i want $class to be a reference to my variable inside the function.
http://jsfiddle.net/yTkqp/

I'm up for grabs for suggestions to alternative solutions.

Answer 1

Variable variables don't exist in Sass. For the mixin you've presented, you can either pass it a single list containing 2 values or pass 2 values.

Option #1:

$custom : #f20;
@mixin colorbyclass($value) {
  &.#{nth($value, 1)} {
    background: nth($value, 2);
  }
}
.container {
  div {
    width:20px;
    height:20px;
    @include colorbyclass(custom $custom);
  }
}

Option #2:

$custom : #f20;
@mixin colorbyclass($class, $color) {
  &.#{$class} {
    background: $color;
  }
}
.container {
  div {
    width:20px;
    height:20px;
    @include colorbyclass(custom, $custom);
  }
}

Though, they look just as verbose as not using a mixin at all:

.container {
  div {
    width:20px;
    height:20px;
    &.custom {
        background: $custom; // could easily be replaced with a mixin that sets a bg color + other stuff
    }
  }
}

Answer 2

I don't think you can use variable variables in sass. This other question seems to answer your question: using hash with scss