Edit in JSFiddle

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

myApp.controller( 'MyCtrl', [ '$scope', function ( $scope ) {}]);

myApp.directive( 'myngFocused', [ '$compile', function ( $compile ) {
    return function ( scope, element, attr ) {
        var scopeVar = attr.myngFocused;

        attr.$set( 'myngFocused' );
        attr.$set( 'ngFocus', scopeVar + ' = true' );
        attr.$set( 'ngBlur', scopeVar + ' = false' );

        $compile( element )( scope );
    };
}]);

<div ng-controller="MyCtrl">
    <input type="text" placeholder="Focus me!" myng-focused="focused"/>
    <pre ng-show="focused">I'm focused!!!</pre>
</div>