Recipe 1.15. Exiting a Method

Problem

You want to exit a method.

Solution

Methods terminate automatically after the last statement within the method executes. Use a return statement to exit a method before reaching its end.

Discussion

The return statement exits the current method and the ActionScript interpreter continues execution of the code that initially invoked the method. Any statements within the method body that follow a return statement are ignored.

private function sampleFunction (  ):void {   return;   trace("Never called"); } // Called from within another method: sampleFunction(  ); // Execution continues here after returning from the sampleFuction(  ) invocation

In the preceding example, the return statement causes the method to terminate before performing any actions, so it isn't a very useful method. More commonly, you will use a return statement to exit a method under certain conditions. This example exits the method if the password is wrong:

private function checkPassword (password:String):void {   // If password is not "SimonSays", exit the function.   if (password != "SimonSays") {     return;   }   // Otherwise, perform the rest of the actions.   showForm ("TreasureMap"); } // This method call uses the wrong password, so the  // function exits. checkPassword("MotherMayI"); // This method call uses the correct password, so the function  // shows the TreasureMap form. checkPassword("SimonSays");

In the preceding example, you may notice that the method is declared as void, yet it is possible to use a return statement within the method without getting a compiler error. When a return statement is used simply to exit from a method, it is valid within a method declared as void.

In ActionScript 2.0, the function was Void. In ActionScript 3.0, it is lowercase void.

However, if you attempt to actually return a value in such a method, the compiler generates an error.

private function sampleMethod (  ):void {   return "some value";  // This causes the compiler to generate an error. }