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 <[email protected]>
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.
>
