Named argument in actionscript

If I have a function like:

        public function defaultValues(first = 1,second =2,third = 3)
        {
            trace(first);
            trace(second);
       开发者_开发知识库     trace(third);
        }

How can I call this function by only passing in a value for second = 20 ?

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ActionScript3 does not support named parameters. If you really want this behavior, you can use an associative array... but I don't recommend it unless you really want to be dynamic :

public function defaultValues(params:Object)
{
    var first = "first" in params ? params.first : 1;
    var second = "second" in params ? params.second : 2;
    var third = params.third ? params.third : 3;

    trace(first);
    trace(second);
    trace(third);
}

Then, you can call it:

defaultValues({second: 99});

---

You should call:

defaultValues(1, 20);

BTW it is extremely bad practice not to use strict typing in ActionScript. Maybe you have Javascript or ActionScript 2 background but it can't be excuse. So your method should looks like:

    public function defaultValues(first:int = 1,second:int =2,third:int = 3) : void
    {
        trace(first);
        trace(second);
        trace(third);
    }

---

You could have a parameter class for only that function. Although it is a bit of an overkill, it will give you optional parameters which are strictly typed. It does however require a lot more coding.

class DefaultValuesParams {
    public var first:int = 1;
    public var second:int = 2;
    public var third:int = 3;
}

var optionalArgs:DefaultValueParams = new DefaultValueParams();
optinalArgs.second = 20;
defaultValues(optionalArgs);

---

You may want to overload the method with only one parameter and from the overloaded method call the 3 param method with default values for first and third.