Passing arguments into mouseEvent function - actionscript-3

Question

This seems simple in other languages, but I don't understand the error. I have 7 buttons that I would like to each take my gallery movieclip to a certain frame when you click on them.
Error: 1067: Implicit coercion of a value of type int to an unrelated type flash.events:MouseEvent.
Error: 1136: Incorrect number of arguments. Expected 2.
Error: 1067: Implicit coercion of a value of type void to an unrelated type Function.
Any help?
function gotoImage(event:MouseEvent, frameParam:int):void
{
MovieClip(this.root).gallery.gotoAndStop(frameParam);
}
t1.addEventListener(MouseEvent.CLICK, gotoImage(1));
t2.addEventListener(MouseEvent.CLICK, gotoImage(2));
t3.addEventListener(MouseEvent.CLICK, gotoImage(3));
t4.addEventListener(MouseEvent.CLICK, gotoImage(4));
t5.addEventListener(MouseEvent.CLICK, gotoImage(5));
t6.addEventListener(MouseEvent.CLICK, gotoImage(6));
t7.addEventListener(MouseEvent.CLICK, gotoImage(7));

Answer 1

You've got two things off with your code:
First, in ActionScript, event handlers always have the same signature:
function someHandler(e:Event):void { .. }
Sometimes the Event argument is a more specific subclass of Event, such as MouseEvent, but there is always just one argument.
The addEventListener method needs a function itself, not the result of invoking a function.
// Here's a function:
function multiply(i1:int, i2:int):int { return i1 * i2; }
// Here's assigning the result of **invoking** a function:
var result:int = multiply(2,3);
// Here's assigning a **function itself** to a variable:
var f:Function = multiply;
// You can invoke the function via the variable f in two different ways:
var result1 = f(2,3);
var result2 = f.apply(null, [2,3]);
So, you'll need to change your code to follow the above to points. You'll have to associate the buttons with jumping to a specific frame one of two ways:
Simple but repetitive: Use a separate handler for each button, with the frame hard coded into each handler.
1a. Named functions (most verbose):
function onT1Click(e:MouseEvent):void {
MovieClip(this.root).gallery.gotoAndStop(1);
}
t1.addEventListener(MouseEvent.CLICK, onT1Click);
// etc. etc.
1b. Anonymous functions:
t1.addEventListener(MouseEvent.CLICK, function(e:Event):void {
MovieClip(this.root).gallery.gotoAndStop(1);
});
// etc. etc.
More elegant: Use the same handler, and store the association between button and frame elsewhere, such as in a Dictionary. If you stick with your naming convention you could even fill the Dictionary in a for loop getting the buttons by name:
var buttonToFrame:Dictionary = new Dictionary();
for(var i:int = 1; i < 8; i++) {
var btn:Button = this["t" + i.toString()];
buttonToFrame[btn] = i;
btn.addEventListener(MouseEvent.CLICK, onClick);
}
function onClick(e:MouseEvent):void {
var btn:Button = Button(e.currentTarget);
var frameNum:int = buttonToFrame[btn];
MovieClip(this.root).gallery.gotoAndStop(frameNum);
}

Answer 2

Just change this
t1.addEventListener(MouseEvent.CLICK, function(me:MouseEvent):void{ gotoImage(me, 1)});
t2.addEventListener(MouseEvent.CLICK, function(me:MouseEvent):void{ gotoImage(me, 2)});
and so on...

Answer 3

This is possible with a roundabout approach. For the event handler, use a function that returns a nested anonymous function.
private var textFieldA:TextField = new TextField;
private var textFieldB:TextField = new TextField;
public function setParameterizedTextWhenTextFieldsAreClicked ():void {
addChild(textFieldA);
textFieldA.text = 'Text field A';
textFieldA.addEventListener(MouseEvent.CLICK, showCustomMessage("One"));
addChild(textFieldB);
textFieldB.text = 'Text field B';
textFieldB.y = 20;
textFieldB.addEventListener(MouseEvent.CLICK, showCustomMessage("Two"));
// NOTE: We must use strongly referenced listeners because weakly referenced
// listeners **will get garbage collected** because we're returning
// an anonymous function, which gets defined in the global namespace and
// thus, the garbage collector does not have anything pointing to it.
}
private function showCustomMessage (message:String):Function {
// NOTE: You can store the following function to a class variable
// to keep it in memory, which would let you use weakly referenced
// listeners when using this as an event handler. Many people
// would find that awkward. I would discourage that.
return function (e:MouseEvent):void {
var textField:TextField = e.target as TextField;
textField.text = message; // "message" argument is available because
// this function's scope is kept in memory.
}
}
Bear in mind, the use of anonymous functions and reliance on function scope being kept in memory seem to present garbage collection complications.