How to create a function that can return anything in actionscript

Question

How do make a function return *, by star, I mean the function is able to return anything, and then I can typecast it accordingly?

private function get_current_files_view():TileList
    {
        var tlist:TileList;
        //switch(this[fm_model.files_display_type])
        switch(vs_file_display.selectedChild)
        {
            case cvs_user_files:    
                tlist = tlist_files;
                break;

            case bx_shared_data:                    
                tlist = tlist_shared_with_me;
                break;
            default:    
                throw new Error('Invalid container found');
        }
        return tlist;
    }

Suppose in this function, I want this function to return both tilelist and datagrid (according to the case) what should be changed.

Plz let me know Thanks you.

JeffryHouser · Accepted Answer · 2011-01-24 19:49:21Z

11

Suppose in this function, I want this function to return both tilelist and datagrid (according to the case) what should be changed.

If that is the case, then you should return ListBase, which is a parent class of both the List and the DataGrid.

I you want to be able to return any object, you can specify the return type as Object.

If you really want to return anything, including primitve values, such as integers you can use the *, as was stated in another answer. IF this is truly what you need, my intuition is that you may need to refactor your application.

answered Jan 24, 2011 at 19:49

JeffryHouser

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1 Comment

Brian Genisio Over a year ago

+1 Yes, I agree with that. Very often (but certainly not always), * is a cop out... especially if you know you want it to be one of two types only. I like using ListBase. Returning * is great when you really CAN return anything. If we ever get generics in AS3, then the majority of * returns will likely be generic returns instead.

Brian Genisio · Accepted Answer · 2011-01-24 20:47:20Z

8

You don't NEED to define a return type. If you don't, then you can return anything or nothing (not recommended):

private function get_current_files_view() { }

Or, you can define it that it must return something, but anything

private function get_current_files_view():* { }

Or, you could always use an interface or base class if you want to be specific:

private function get_current_files_view():ISomeInterface {}

Does this help? Or am I completely misunderstanding your question?

edited Jan 24, 2011 at 20:47

answered Jan 24, 2011 at 19:08

Brian Genisio

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4 Comments

JeffryHouser Over a year ago

+1 for the suggestion to use an interface. I believe that is a much better development approach than having an * as the return type.

Adam Harte Over a year ago

The Flex compiler in strict mode wont accept a method with no return type. It is best practice to always define a return type.

Brian Genisio Over a year ago

@TandemAdam: Agreed. I like to specifically define my routines as functions (return something... *, Type, Object, etc) or procedures (returns void). It is clear to the caller whether to expect a return or not. I will edit my response to add that suggestion. My variables, however, I am happy to mix in static typing and dynamic typing. In functions, however, we should specify something.

JeffryHouser Over a year ago

@TandemAdam I think the claim that the Flex Compiler "won't accept a method with no return type" in strict mode is a bit inaccurate. The Flex Compiler gives a warning, but a compile time warning doesn't prevent you from compiling the app.

Chunky Chunk · Accepted Answer · 2011-01-24 19:10:40Z

2

private function whatsMyObject:(parameter:*):*
     {
     switch  (parameter.constructor)
             {
             case TileList:     trace("parameter is TileList");
                                break;

             case DataGrid:     trace("parameter is DataGrid");
                                break;

             default:           trace("parameter is neither TileList nor DataGrid");
             }

     return parameter;
     }

answered Jan 24, 2011 at 19:10

Chunky Chunk

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2 Comments

Chris Burt-Brown Over a year ago

Always better to use is rather than the undocumented constructor property. It'll catch subclasses too.

Chunky Chunk Over a year ago

constructor is documented: help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/…

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