Edit in JSFiddle

var testapp = angular.module('testapp', []);

testapp.controller('parentController', ['$scope', '$window', function($scope, $window) {
    $scope.onPrimary1Click = function() {
        alert('Primary1 clicked');    
    };
    $scope.primary1Label = "Prime1"
}]);

testapp.directive('primary', function() {
    return {
        restrict: 'C',
        link: function(scope, element, attrs) {
            element.addClass('btn btn-primary');
        }
    }
});

testapp.directive('secondary', function() {
    return {
        restrict: 'C',
        link: function(scope, element, attrs) {
            element.addClass('btn');
        }
    }
});

testapp.directive('buttonBar', function() {
    return {
        restrict: 'EA',
        template: '<div class="span4 well clearfix"><div class="primary-block pull-right"></div><div class="secondary-block"></div></div>',
        replace: true,
        transclude: true,
        scope: {},
        controller: ['$scope', '$element', '$transclude', function ($scope, $element, $transclude) {
            $transclude(function(clone) {
                var primaryBlock = $element.find('div.primary-block');
                var secondaryBlock = $element.find('div.secondary-block');
                var transcludedButtons = clone.filter(':button'); 
                angular.forEach(transcludedButtons, function(e) {
                    if (angular.element(e).hasClass('primary')) {
                        primaryBlock.append(e);
                    } else if (angular.element(e).hasClass('secondary')) {
                        secondaryBlock.append(e);
                    }
                });
            });
        }],
    };
});

<div ng-controller="parentController">    
    <button-bar>
        <button class="primary" ng-click="onPrimary1Click()">{{primary1Label}}</button>
        <button class="primary">Primary2</button>
        <button class="secondary">Secondary1</button>
    </button-bar>
</div>

.primary, .secondary {
    margin-left: 5px;
    margin-right: 5px;
}