Ember bind class property not working

Below is my ember controller defined search_property and i have callback bind method portfolio_name for class name, i have changed search_property and currentSortIcon in code but my binding method is not invoking.

App.MemberCreditPortfoliosIndexController = Ember.ArrayController.extend(
          search_property: null
      sort_data: (property) ->
          @set('search_property', property)
          @set('sort_ascending', !@get('sort_ascending'))
          if @get('sort_ascending') == true
            @set('search_order', 'ASC')
            sortIcon = 'icon-up'
            #@set('sort_ascending', false)
          else
            @set('search_order', 'DESC')
            sortIcon = 'icon-down'
            #@set('sort_ascending', true)
          @transitionTo({page: 1, search_string: @get('search_string'),search_property: property, search_order: @get('search_string')})
          @set 'currentSortIcon', sortIcon


      portfolio_name: (->
          @getSortIcon('portfolio_name')
        ).property('search_property', 'currentSortIcon')

    )

i have written my bind-attr for class in handlebars views.

<th {{action 'sort_data' 'portfolio_name' }} ><span {{bind-attr class="portfolio_name :pull-right"}}></span>Portfolio Name</th>

please let me know if anything i missed or wrong.