R – how to indicate an unset default parameter of type Number in Flex3

actionscript-3apache-flexflex3

for String and Object type, I can set the default parameter to null to indicate that it was not set by the caller. Is there a mechanism in flex3 to do the same for the Number type?

So for instance:
public function myMethod( stringVar:String=null, ObjectVar:Object=null, numberVar:Number )
{
…
}

I could do the following, but it just feels ugly

public function myMethod( numberVarObj:Object=null ) 
{
 var numberVarSet:Boolean=true;
if( numberVarObj == null ) {
     numberVarSet = false;
 }

 and then everywhere I want to use numberVar I can check for numberVarSet and cast as a Number.

Best Answer

I suppose you could always try:

var numberVar:* = null;

And then set it to a number when you want . . . It would be nice to have a solution that is strongly typed though.

Another option, as specified in Adobe's Docs (scroll down to default values), would be to treat the value NaN as null. However, if your data has ANY chance of containing a NaN value, this is a horrible idea.

Related Solutions

R – flex3 type casting

The second type of casting has different behaviour for top level(http://livedocs.adobe.com/flex/2/langref/) types, e.g. Array(obj) does not cast in the straightforward way you describe; it creates a new Array if possible from obj, even if obj is an Array.

I'm sure the times this would cause unexpected behaviour would be rare but I always use "as" for this reason. It means if I do

int(str)

I know it's a cast in the "attempt to convert" sense of the word not in the "I promise it is" sense.

ref: got some confirmation on this from http://raghuonflex.wordpress.com/2007/07/27/casting-vs-the-as-operator/

R – How set background of row dynamic using flex

The solution is to make a class that extends DataGrid and override the drawRowBackground method, which is responsible for drawing a colored rectangle behind the row items.

The drawRowBackground method is passed a default color, as well as the index of your current data item, so you can retrieve the current item, grab a custom color property from it, and pass that color into the super.drawRowBackground() call.

override protected function drawRowBackground(s:Sprite, rowIndex:int, 
                                                y:Number, height:Number,
                                                color:uint, dataIndex:int):void 
{
    if (dataIndex < dataProvider.length && dataProvider[dataIndex])
    {
        color = dataProvider[dataIndex].color;
    }
    super.drawRowBackground(s, rowIndex, y, height, color, dataIndex);
}

Best Answer

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R – flex3 type casting

R – How set background of row dynamic using flex

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