RE: [flexcoders] any performance hit using "as"?

[Ted Patrick]

Using ‘as’ can get confusing as it has a subtle gotcha. ‘as’ will return the object if it inherits from the target Class else it returns null.   This is great behavior until you try it with Classes that inherit from Proxy.   Example: myVar will be null, 100% of the time!!!   var aCollection:ArrayCollection; var myArray:Array;   aCollection = new ArrayCollection( [1,2,3] ); myArray = aCollection as Array;   ArrayCollection does not inherit from Array, it holds an array internally and uses Proxy to provide an alternative interface.   Cheers,   Ted Patrick Flex Evangelist Adobe Systems Incorporated     From: flexcoders@yahoogroups.com [mailto:flexcoders@yahoogroups.com] On Behalf Of Pan Troglodytes Sent: Tuesday, August 08, 2006 8:11 AM To: flexcoders@yahoogroups.com Subject: Re: [flexcoders] any performance hit using "as"?   Thanks for the reply, Matt.  Is there any performance difference between all three?  I'm curious if doing any casting at all is a performance hit. On 8/7/06, Matt Chotin <[EMAIL PROTECTED]com> wrote: I don't think there should be a performance difference between the two.   Matt   From: [EMAIL PROTECTED]ups.com [mailto:[EMAIL PROTECTED]ups.com] On Behalf Of Pan Troglodytes Sent: Monday, August 07, 2006 9:21 AM To: flexcoders Subject: [flexcoders] any performance hit using "as"?   I tend to like to make my code autosense for me, so sometimes I do things like this: MyObjectType(grid.selectedItem).somefield = 3; I assume that adds no overhead, since it is a straight cast (though I could be wrong), since I have seen runtime errors specifically telling me my cast was wrong.  But sometimes with Array, I have to use "as" because it gets a cast confused with a new array contructor.  So I'm wondering what the difference in performance is, if any. Given then grid.selectedItem is MyObjectType, consider the following statements: grid.selectedItem.somefield = 3; MyObjectType(grid.selectedItem).somefield = 3; (grid.selectedItem as MyObjectType).somefield = 3; Is there any runtime performance difference to them?  I only just now read the help on "as" I noticed that if it is NOT the desired type, it returns null.  That totally messes with my brain, coming from a Delphi background where as throws an exception if it is not the right type.  But the thrust of my question involves them being the desired type. -- Jason -- Jason __._,_.___ -- Flexcoders Mailing List FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com SPONSORED LINKS Web site design development Computer software development Software design and development Macromedia flex Software development best practice YAHOO! GROUPS LINKS  Visit your group "flexcoders" on the web.    To unsubscribe from this group, send an email to:  [EMAIL PROTECTED]    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. __,_._,___