How to define a dynamic mixin or function name in SASS?

I want to dynamically create mixins in SASS, named after each item in the list, but it doesn't seem to work.

I tried this but I get an error:

$event-icons: fair, concert, art-show, conference, dance-show, film, party, festival, theatre, launch
@each $event-icon in $event-icons
  @mixin event-icon-#{$event-icon}
    background-position: -($event-icon-width * $i) 0

Error:

Invalid CSS after "": expected expression (e.g. 1px, bold), was "#{$event-icon}"

Is this usage not supported by SASS? I couldn't find anything in the manual about it.

Solution

Variable interpolation in @mixins does not appear to be supported currently.

The SASS documentation calls this #{} interpolation and describes it like this:

Interpolation: #{}

You can also use SassScript variables in selectors and property names using #{} interpolation syntax:

$name: foo;
$attr: border;
p.#{$name} {
  #{$attr}-color: blue;
}

Per the documentation, interpolation of variable names only appears to be supported for selectors and property names, and not for @mixins. If you'd like that feature, you may want to file an Issue for it, although this one may already be tracking what you're describing.

Edit: Are you sure you need to use a @mixin to accomplish the kind of styling you're talking about? Could you just use a selector with interpolation? For example, would this work:

$event-icons: fair, concert, art-show, conference, dance-show, film, party, festival, theatre, launch
@for $i from 1 to length($event-icons)
  $event-icon: nth($event-icons, $i)
  .event-icon-#{$event-icon}
    background-position: -($event-icon-width * $i) 0