RE: [flexcoders] AS3 class constructors can't be private? Abstract classes?

Fri, 10 Feb 2006 09:54:40 -0800

Well you could throw an Error if the parameter passed in was null too…

 

From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Geoffrey Williams
Sent: Friday, February 10, 2006 9:48 AM
To: [email protected]
Subject: RE: [flexcoders] AS3 class constructors can't be private? Abstract classes?

 

I had seen that before and didn’t like it because you could just use:

 

var _singleton:MySingleton = new MySingleton (null);

 

In any case, for anyone interested, I ended up doing something similar to the code below:

 

package whatever {

            public class SingletonClass {

                        public function SingletonClass () {

                                    if (Instantiation.locked) throw new Error ("Singleton class cannot be instantiated using the constructor.");

                        }

                        private static var __instance:SingletonClass;

                        public static function get instance ():SingletonClass {

                                    if (!__instance) {

                                                Instantiation.locked = false;

                                                __instance = new SingletonClass ();

                                                Instantiation.locked = true;

                                    }

                                    return __instance;

                        }

            }

}

class Instantiation {

            public static var locked:Boolean = true;

}

From: [email protected] [mailto:[email protected]] On Behalf Of Matt Chotin
Sent: Friday, February 10, 2006 12:24 PM
To: [email protected]
Subject: RE: [flexcoders] AS3 class constructors can't be private? Abstract classes?

 

They did, we discussed ad infinitum, this is what we came up with.  Maybe we can improve it later but this is what we’re getting for now.  Trust us that we spent a long time discussing internally.

 

Re the package stuff, it’s about the file not the package.

 

MySingleton.as

 

package whatever {

  public class MySingleton {

    public function MySingleton(singletonEnforcer:MySingletonEnforcer) { … }

    private static var instance:MySingleton;

    pubic function getInstance():MySingleton {

      if (instance == null)

        instance = new MySingleton(new MySingletonEnforcer());

      return instance;

    }

    …

  }

}

 

//this is in MySingleton.as but is outside the package block

class MySingletonEnforcer {}

 

And that’s it.

 

Matt

 

From: [email protected] [mailto:[email protected]] On Behalf Of Carlos Rovira
Sent: Friday, February 10, 2006 7:47 AM
To: [email protected]
Subject: Re: [flexcoders] AS3 class constructors can't be private? Abstract classes?

 

I was supposing that don't have private constructors was due to the alpha state of the player, but it seems like is something deliberated. IMHO, I don't agree with this design languaje issue cause patterns like singletons are widely used and people expect to use in the standard way. I don't want to argue but would like the guys behind this responsability to think about it a bit and think about what their users expect to find when deal with the languaje. Thanks for listening :)

2006/2/10, Johannes Nel <[EMAIL PROTECTED]>:

so even if i create a private class that is only accecible in that package (and then on package level declare a accesor for it) the only way i can be certain that class will only be created once is by having nothing else in that package. this does not seem right.

 

On 2/10/06, Matt Chotin < [EMAIL PROTECTED]> wrote:

You have to simulate private constructors by having the constructor take a class that is inaccessible to other classes (namely putting that class in the same file as the singleton outside of the package block).  Unfortunately I believe the rule is that the constructor of the class has to have the same visibility as the class itself.  So public classes need public constructors, internal classes get internal constructors, etc.

 

Matt

 

From: [email protected] [mailto:[email protected]] On Behalf Of Johannes Nel
Sent: Thursday, February 09, 2006 4:51 PM
To: [email protected]
Subject: Re: [flexcoders] AS3 class constructors can't be private? Abstract classes?

 

abstract classes i am not expecting, private constructers i certainly hope for

On 2/9/06, Carlos Rovira <[EMAIL PROTECTED] > wrote:

Hi,

I was trying to migrate some classes from AS2 to AS3 and notice that can't mark the class constructor as private. Is that correct or there's a workaround? if not have plans to implement private constructors.

and abstract classes?

Thanks in advance.

--
::| Carlos Rovira
::| http://www.carlosrovira.com





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