no-new-mixins.md

no-new-mixins

Using mixins to share code appears easy at first. But they add significant complexity as a project grows. Furthermore, the Octane programming model eliminates the need to use them in favor of native class semantics and other primitives.

For practical strategies on removing mixins see this discourse thread.

For more details and examples of how mixins create problems down-the-line, see these excellent blog posts:

• Mixins Considered Harmful
• Why Are Mixins Considered Harmful?

Examples

Examples of incorrect code for this rule:

// my-mixin.js
export default Mixin.create({
  isValidClassName(classname) {
    return Boolean(className.match('-class'));
  },

  hideModal(value) {
    this.set('isHidden', value);
  }
});

// my-component.js
import myMixin from 'my-mixin';

export default Component.extend(myMixin, {
  aComputedProperty: computed('obj', function() {
    return this.isValidClassName(get(obj, 'className'));
  })
});

Examples of correct code for this rule:

// my-utils.js
export function isValidClassName(classname) {
  return Boolean(className.match('-class'));
}

export function hideModal(obj, value) {
  set(obj, 'isHidden', value);
}

// my-component.js
import { isValidClassName } from 'my-utils';

export default Component.extend({
  aComputedProperty: computed('obj', function() {
    return isValidClassName(get(obj, 'className'));
  })
});

Related Rules

• no-mixins