Accessing Methods and Properties via getChildByName

[f-zero]

Hi guys

I seem to be having a bit of a problem here.
I'm generating a load of class instances using the following code:

maxpersons=25;

for (var i:Number=1;i<=maxpersons;i++)
{
var person:Person = new Person;
person.name="person"+i;
game.addChild(person);
}


OK. I then need to run through each of them and check for a collision with an object from the main stage (called redDot), which I pass to a method (called doDamage) within the class. I'm using the following code:

for (i=1;i<=maxpersons;i++)
{
if (game.getChildByName("person"+i).hitTestObject(red Dot))
{
game.getChildByName("person"+i).doDamage(redDot);
}
}

I keep getting an error saying "1061: Call to a possibly undefined method doDamage through a reference with static type flash.displayisplayObject."!

It just won't work. I've tried altering the code to:

game["person"+i].doDamage(redDot);

but I get an unexpected trace output saying "TypeError: Error #1010: A term is undefined and has no properties."

Maybe I'm going about it the wrong way. Can someone please shed some light on this, cos I haven't got a clue whats going on! Thanks!

[Schfifty Five]

First, it should be:
var person:Person = new Person();
not
var person:Person = new Person;

And try this instead:

for (i=1;i<=maxpersons;i++)
{
if ((game.getChildByName("person"+i) as Person).hitTestObject(redDot))
{
(game.getChildByName("person"+i) as Person).doDamage(redDot);
}
}

[5TonsOfFlax]

I'd also suggest putting all your persons in an array so that you don't have to use getChildByName. It'll be neater and faster.

The main problem you were having however was the type mismatch. getChildByName returns a DisplayObject, so if you need to call a method defined in a more specific class, you have to cast it to that class first so the compiler can know what you're trying to do.

[f-zero]

Oh man that code correction worked perfectly!!! Thanks guys!!
Now I can finally continue my game. Thanks again!

[Schfifty Five]

I'd also suggest putting all your persons in an array so that you don't have to use getChildByName. It'll be neater and faster.

The main problem you were having however was the type mismatch. getChildByName returns a DisplayObject, so if you need to call a method defined in a more specific class, you have to cast it to that class first so the compiler can know what you're trying to do.

Right, thanks for explaining it to him, I probably should have :P

[Vanth99]

I would like to see how you would organize this in an array. I have a similare issue, but it's an extended button class that I have added a bunch of variable data. I have not considered adding each extended button child in a container, and also I would like to see an example of code for the array concept. I tried casing the button with the as class name. The compiler did not complain but the code hangs.

[mothmann]

for (var i:Number=1;i<=maxpersons;i++)
{
//////var person:Person = new Person;///////
person.name="person"+i;
game.addChild(person);
}

the marked line is a very very bad way to do this. the first time the loop goes through it will create a var named person of type Person. you give it a name. then the 2nd time the loop goes through you overwrite the old variable person with a new one. For some reason tho flash will still have both instances in memory and on stage and certain methods and variables will still be accessible but most will not. To do this you would have to create some kinda object or array to hold all the variables. someone already mentioned using an array which tends to be the most used way of doing this.

var people:Array = new Array();
people[i] = new Person();
game.addChild(people[i]);

or

var people:Object = new Object();
people["person"+i] = new Person();
game.addChild(people["person"+i]);