@import-once hack for sass

gistfile1.txt

//sessions.css.scss - file #1 that i only want to let the _style.scss import be included once

$imported-once-files: ();

@function import-once($name) {
  @if index($imported-once-files, $name) {
    @return false;
  }
  $imported-once-files: append($imported-once-files, $name);
  @return true;
}

@import "style";

body.sessions {
  //normal css for the sessions pages
}



/////////
//donations.css.scss - file that i only want to have _style.scss included once, but if it was already included in sessions, dont double include it

$imported-once-files: ();

@function import-once($name) {
  @if index($imported-once-files, $name) {
    @return false;
  }
  $imported-once-files: append($imported-once-files, $name);
  @return true;
}

@import "style";

body.donations {
  //normal css for the donations pages
}



//////////
//_style.scss shared file with base styles

@if import-once("_style.scss"){
  //base styles and declarations of cool sass-iness that you only want included once
}

Related to sass/sass#139 , they have been considering this for 4 years. Such a pity it's not there yet, it'd be really helpful something like this:

@import "style" !once;