Sass - import variables to be used in mixin

Question

Is there a way to import external variables into mixins?
I would like to generate a variablename from a mixin argument
and then call it from an external source. Does this make any sense?

---

variables.scss

/* Striped status bar variables ******************************************/

$greyFirstGradientStartColor: #999999;
$greyFirstGradientEndColor: #d3cfcf;
$greySecondGradientStartColor: #ababab;
$greySecondGradientEndColor: #595959;

---

mixins.scss

@import variables.scss

[...]

@mixin gradient-repeating($color, $deg, $firstWidth, $space, $secondWidth){

  background-image:
    repeating-linear-gradient(
      $deg,
      $(#{$color}FirstGradientStartColor),
      $(#{$color}FirstGradientEndColor) $firstWidth+px,
      $(#{$color}SecondGradientStartColor) ($firstWidth+$space)+px,
      $(#{$color}SecondGradientStartColor) $secondWidth+px
  );
}

---

my-main-css-file.scss

@import variables.scss;  
@import mixins.scss;  

[...]

@include gradient-repeating(grey, -45, 20, 0, 20);  

Answer 1

No. Variable variables do not exist in Sass. Lists or lists of lists are typically used instead.

Your mixin could be written like this:

$grey-gradient: #999999 #d3cfcf, #ababab #595959;

@mixin gradient-repeating($color, $deg, $firstWidth, $space, $secondWidth){
    $firstColor: nth($color, 1);
    $secondColor: nth($color, 2);
    background-image:
        repeating-linear-gradient(
          $deg,
          nth($firstColor, 1),
          nth($firstColor, 2) $firstWidth+px,
          nth($secondColor, 1) ($firstWidth+$space)+px,
          nth($secondColor, 1) $secondWidth+px
        );
}

.foo {
    @include gradient-repeating($grey-gradient, -45, 20, 0, 20);
}