Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.4)
// Compass (v1.0.1)
// ----

$font-faces: (
  ('Helvetica-Neue', 'helveticaneue'),
  ('Helvetica-Neue-Bold', 'helveticaneue-bold-webfont', 700),
  ('Helvetica-Neue-Medium', 'helveticaneue-medium-webfont', 500),
  ('Avant-Garde-Black', 'itcavantgardestd-bk-webfont', 700),
  ('Avant-Garde-Bold', 'itcavantgardestd-bold-webfont', 500),
  ('Avant-Garde-Demi', 'itcavantgardestd-demi-webfont'),
  ('Avant-Garde-XLT', 'itcavantgardestd-xlt-webfont', 100)
);
$font-path: '../fonts/';

// font family mixin
@mixin font($font, $style: normal, $weight: normal) {
  font-family: $font, Helvetica, Arial, sans-serif;
  font-style:  $style;
  font-weight: $weight;
}

@each $font-face in $font-faces {
  
  $font-css-name: nth($font-face, 1);
  $font-url-name: nth($font-face, 2);
  
  $font-weight: 'normal';
  $font-style: 'normal';
  
  // check if we need to change the weight or style
  @if (length($font-face) > 2) {
    $font-weight: nth($font-face, 3);
  }
  @if (length($font-face) > 3) {
    $font-style: nth($font-face, 4);
  }
  
  // generate all font faces using their appropriate weights & styles
  @font-face {
    font-family: $font-css-name;
    font-weight: $font-weight;
    font-style: $font-style;
    src: url('#{$font-path}#{$font-url-name}.eot');
    src: url('#{$font-path}#{$font-url-name}.eot?') format('eot'),
         url('#{$font-path}#{$font-url-name}.woff') format('woff'),
         url('#{$font-path}#{$font-url-name}.ttf')  format('truetype');
  }
  
  // generate placeholders so we can extend when we need to use a font
  %#{$font-css-name} {
    @include font($font-css-name, $font-style, $font-weight);
  }
}

.test-block {
  @extend %Helvetica-Neue;
}

SassMeister-output.css

@font-face {
  font-family: "Helvetica-Neue";
  font-weight: "normal";
  font-style: "normal";
  src: url("../fonts/helveticaneue.eot");
  src: url("../fonts/helveticaneue.eot?") format("eot"), url("../fonts/helveticaneue.woff") format("woff"), url("../fonts/helveticaneue.ttf") format("truetype");
}
.test-block {
  font-family: "Helvetica-Neue", Helvetica, Arial, sans-serif;
  font-style: "normal";
  font-weight: "normal";
}

@font-face {
  font-family: "Helvetica-Neue-Bold";
  font-weight: 700;
  font-style: "normal";
  src: url("../fonts/helveticaneue-bold-webfont.eot");
  src: url("../fonts/helveticaneue-bold-webfont.eot?") format("eot"), url("../fonts/helveticaneue-bold-webfont.woff") format("woff"), url("../fonts/helveticaneue-bold-webfont.ttf") format("truetype");
}
@font-face {
  font-family: "Helvetica-Neue-Medium";
  font-weight: 500;
  font-style: "normal";
  src: url("../fonts/helveticaneue-medium-webfont.eot");
  src: url("../fonts/helveticaneue-medium-webfont.eot?") format("eot"), url("../fonts/helveticaneue-medium-webfont.woff") format("woff"), url("../fonts/helveticaneue-medium-webfont.ttf") format("truetype");
}
@font-face {
  font-family: "Avant-Garde-Black";
  font-weight: 700;
  font-style: "normal";
  src: url("../fonts/itcavantgardestd-bk-webfont.eot");
  src: url("../fonts/itcavantgardestd-bk-webfont.eot?") format("eot"), url("../fonts/itcavantgardestd-bk-webfont.woff") format("woff"), url("../fonts/itcavantgardestd-bk-webfont.ttf") format("truetype");
}
@font-face {
  font-family: "Avant-Garde-Bold";
  font-weight: 500;
  font-style: "normal";
  src: url("../fonts/itcavantgardestd-bold-webfont.eot");
  src: url("../fonts/itcavantgardestd-bold-webfont.eot?") format("eot"), url("../fonts/itcavantgardestd-bold-webfont.woff") format("woff"), url("../fonts/itcavantgardestd-bold-webfont.ttf") format("truetype");
}
@font-face {
  font-family: "Avant-Garde-Demi";
  font-weight: "normal";
  font-style: "normal";
  src: url("../fonts/itcavantgardestd-demi-webfont.eot");
  src: url("../fonts/itcavantgardestd-demi-webfont.eot?") format("eot"), url("../fonts/itcavantgardestd-demi-webfont.woff") format("woff"), url("../fonts/itcavantgardestd-demi-webfont.ttf") format("truetype");
}
@font-face {
  font-family: "Avant-Garde-XLT";
  font-weight: 100;
  font-style: "normal";
  src: url("../fonts/itcavantgardestd-xlt-webfont.eot");
  src: url("../fonts/itcavantgardestd-xlt-webfont.eot?") format("eot"), url("../fonts/itcavantgardestd-xlt-webfont.woff") format("woff"), url("../fonts/itcavantgardestd-xlt-webfont.ttf") format("truetype");
}