[QUESTION] What is the idiomatic way to append and remove classes from components?

@deiga we are doing something like this.

{
      defaults: ->
        {
          name: type
          type: type
          tagName: 'div'
          socialElement: 'web'
          icons: {
            twitter: 'fa-twitter-square'
            linkedin: 'fa-linkedin-square'
            web: 'fa-globe'
          }
          components: {
            type: 'link'
            toolbar: []
          }
          attributes: {
            'class': "social_element fa fa-twitter-square"
          }
          traits: [
            {
              type: 'select'
              label: 'Icon'
              name: 'socialElement'
              changeProp: 1
              options: []
            }, {
              name: 'href'
              changeProp: 1
            }
          ]
        }

      init: ->
        this.listenTo(this, 'change:href', @onSocialUrlChange.bind(this))
        this.listenTo(this, 'change:socialElement', @onSocialIconChange.bind(this))

        @initSettings()
        @updateTraitValues()

      updateTraitValues: ->
        @_initSocialIcon()

      _initSocialIcon: ->
        icons = @attributes.icons
        classes = @getClasses()
        icon = ''
        for cls in classes
          icon = Object.keys(icons).find((key) -> icons[key] == cls)
          break if icon

        this.set('socialElement', icon || 'twitter')

      initSettings: ->
        icons = @attributes.icons
        @updateTrait('socialElement', {
          options: [
            { id: 'twitter', name: 'Twitter', value: 'twitter' },
            { id: 'linkedin', name: 'Linkedin', value: 'linkedin'},
            { id: 'web', name: 'Web', value: 'web' }
          ]
        })

      onSocialIconChange: (model, value) ->
        newClassSet = ['social_element', 'fa']
        model.setClass(newClassSet.concat(@attributes.icons[value]))
    }

I'd attach the trait to some component property instead of the class attribute, and based on the value I'd use properly removeClass and addClass