If you have multiple lines where you need to access properties of a specific type then use 'as' and check for null. If it is one line then use 'is' and cast explicitly.
// use 'as' and check for null when multiple lines accessing a type are involved: public function doSomething(object:UIComponent):void { var button:Button = object as Button; var list:List = object as List; var checkbox:Checkbox = object as Checkbox; // universal UIComponent properties object.visible = true; object.includeInLayout = true; // button specified properties if (button) { button.label = "Button"; button.emphasized = true; } else if (list) { list.labelField = "name"; list.dataProvider = ['1','2','3']; list.selectedIndex = 0; } else if (checkbox) { checkbox.selected = true; checkbox.label = "checkbox"; } } // use 'is' when casting involves a single line. not using 'as' to cast though // Button(object) is less typing than (object as Button) // the (object is Button) already tells us it's a Button. no need for 'as'. just cast as Button() public function doSomething(object:UIComponent):void { object.visible = true; object.includeInLayout = true; if (object is Button) Button(object).label = "Button"; else if (object is List) List(object).labelField = "name"; else if (object is CheckBox) CheckBox(object).selected = true; } // use 'is' when checking for specific types and super types public function checkIfToggle(object:UIComponent):void { if (object is ToggleButtonBase) { return true; } } result = checkIfToggle(new CheckBox()); // true result = checkIfToggle(new RadioButon()); // true result = checkIfToggle(new ToggleButton()); // true result = checkIfToggle(new Button()); // false On Mon, Feb 15, 2016 at 7:30 AM, suresh babu k s <sbab...@hotmail.com> wrote: > Hi,I would like to know best practice for the following approaches1)Doing > 'is' check before casting data using 'as' operator 2)Casting data using > 'as' operator and null testing laterplease share your views > > > > -- > View this message in context: > http://apache-flex-users.2333346.n4.nabble.com/Best-Practice-is-as-and-null-tp11979.html > Sent from the Apache Flex Users mailing list archive at Nabble.com. >