<input type="text" input-disabled="editableInput" />
<button ng-click="editableInput = !editableInput">enable/disable</button>
app.controller("myController", function(){
$scope.editableInput = false;
});
app.directive("inputDisabled", function(){
return function(scope, element, attrs){
scope.$watch(attrs.inputDisabled, function(val){
if(val)
element.removeAttr("disabled");
else
element.attr("disabled", "disabled");
});
}
});