Generated by SassMeister.com. http://sassmeister.com/gist/b4468c11e6f89d964dc1

SassMeister-input-HTML.html

<h1>Flexible mixin arguments</h1>
<p>A small helper function to make your mixin take almost anything thrown at it</p>
<ul>
  <li>Keyword</li>
  <li>Map</li>
  <li>List</li>
  <li>Arguments</li>
</ul>

SassMeister-input.scss

// ----
// Sass (v3.4.7)
// Compass (v1.0.1)
// ----

//
// Map arguments helper
// 
@function map-arguments($keys, $arglist){
  $map: keywords($arglist);
  @if inspect($map)=='()' and length($arglist) > 0 {
      @if type-of(nth($arglist,1))==map{ 
        $map:nth($arglist,1); 
      } 
      @else {
        $list:if(type-of(nth($arglist,1))==list,nth($arglist,1),$arglist);
      @for $i from 1 through length($list){
        $map:map-merge($map,(nth($keys,$i):nth($list,$i)));
      }
    }
  } 
  @return $map;
}

//
// Mixin sample
//
@mixin size($arglist...) {
  $map   : map-arguments(width height, $arglist);

  $width : map-get($map, width);  
  $height: map-get($map, height);  
  $height: $width !default;  
  
  width  : $width; 
  height : $height; 
}

//
// Use examples 
//
.keyword-arguments{
  /* Only width */
  @include size($width: width-value);
  /* Only height */
  @include size($height: height-value);
  /* Normal order */
  @include size($width: width-value, $height: height-value);
  /* Reversed order */
  @include size($height: height-value, $width: width-value);
}

.map-arguments {
  /* Only width */
  $map:(width: width-value);
  @include size($map);
  /* Only height */
  $map:(width: width-value, height: height-value);
  @include size($map);
  /* Normal order */
  $map:(width: width-value, height: height-value);
  @include size($map);
  /* Reversed order */
  $map:(height: height-value, width: width-value);
  @include size($map);
}

.list-arguments {
  /* Only width */
  $list: width-value;
  @include size($list);
  /* Comma */
  $list: width-value, height-value;
  @include size($list);
  /* Space */
  $list: width-value height-value;
  @include size($list);
}

.arguments {
  /* Only width */
  @include size(width-value);
  /* Width and height */
  @include size(width-value, height-value);
}





*{ font-family:sans-serif;}

SassMeister-output.css

.keyword-arguments {
  /* Only width */
  width: width-value;
  height: width-value;
  /* Only height */
  height: height-value;
  /* Normal order */
  width: width-value;
  height: height-value;
  /* Reversed order */
  width: width-value;
  height: height-value;
}

.map-arguments {
  /* Only width */
  width: width-value;
  height: width-value;
  /* Only height */
  width: width-value;
  height: height-value;
  /* Normal order */
  width: width-value;
  height: height-value;
  /* Reversed order */
  width: width-value;
  height: height-value;
}

.list-arguments {
  /* Only width */
  width: width-value;
  height: width-value;
  /* Comma */
  width: width-value;
  height: height-value;
  /* Space */
  width: width-value;
  height: height-value;
}

.arguments {
  /* Only width */
  width: width-value;
  height: width-value;
  /* Width and height */
  width: width-value;
  height: height-value;
}

* {
  font-family: sans-serif;
}

SassMeister-rendered.html

<h1>Flexible mixin arguments</h1>
<p>A small helper function to make your mixin take almost anything thrown at it</p>
<ul>
  <li>Keyword</li>
  <li>Map</li>
  <li>List</li>
  <li>Arguments</li>
</ul>