You can assign default parameter values inline when you first create the mixin: @mixin clearfix($width: ‘auto’) { @if $width == ‘auto’ { // if width is not passed, or empty do this } @else { display: inline-block; width: $width; } }
Update: this answer is outdated. Stay away from the mixins if you can. I warned you! Mixins Are Dead. Long Live Composition At first, I tried to use subcomponents for this and extract FormWidget and InputWidget. However, I abandoned this approach halfway because I wanted a better control over generated inputs and their state. Two … Read more
A mixin is typically used with multiple inheritance. So, in that sense, there’s “no difference”. The detail is that a mixin is rarely useful as a standalone object. For example, say you have a mixin named “ColorAndDimension”, which adds a color property and width and height. Now, you could add ColorAndDimension to a, say, Shape … Read more
I just read about this topic in The Well-Grounded Rubyist (great book, by the way). The author does a better job of explaining than I would so I’ll quote him: No single rule or formula always results in the right design. But it’s useful to keep a couple of considerations in mind when you’re making … Read more
Mixins may contain state, (traditional) traits don’t. Mixins use “implicit conflict resolution”, traits use “explicit conflict resolution” Mixins depends on linearization, traits are flattened. Lecture about traits ad 1. In mixins you can define instance variables. Traits do not allow this. The state must be provided by the composing class (=class using the traits) ad … Read more
The rgba() function can accept a single hex color as well decimal RGB values. For example, this would work just fine: @mixin background-opacity($color, $opacity: 0.3) { background: $color; /* The Fallback */ background: rgba($color, $opacity); } element { @include background-opacity(#333, 0.5); } If you ever need to break the hex color into RGB components, though, … Read more
A mixin is a special kind of multiple inheritance. There are two main situations where mixins are used: You want to provide a lot of optional features for a class. You want to use one particular feature in a lot of different classes. For an example of number one, consider werkzeug’s request and response system. … Read more