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

[Ted Patrick]

Ralf,   (Sorry I think my post was a bit confusing in retrospect.)   ArrayCollection does not inherit from Array thus MyArray will always return null.   aCollection = new ArrayCollection( [1,2,3] ); myArray = aCollection as Array; trace( myArray == null ) //true   With Proxy classes, inheritance stops at Proxy. The Proxy types provide a low level way to redefine and rewire a Classes interface. They are an excellent way to implement the façade or adapter patterns in AS3. How proxy types work internally is a black box (up to the developer), externally the types define an interface by overriding these methods:   callProperty - a method operation deleteProperty - a delete operation getDescendants - E4X Related operation getProperty - a get operation hasProperty - a has operation isAttribute - testing the presence of an attribute in XML/E4X nextName - enumeration support nextNameIndex - enumeration support nextValue - enumeration support setProperty - a set operation   If you want to provide an alternate interface to any object, Proxy is an excellent place to start.   Here is some more background on Proxy:   http://www.onflex.org/ted/2006/04/magic-with-flashutilproxy.php   If you arrived here from FlashLand, Proxy is __resolver on steroids. J   Cheers,   Ted J     From: flexcoders@yahoogroups.com [mailto:flexcoders@yahoogroups.com] On Behalf Of Ralf Bokelberg Sent: Tuesday, August 08, 2006 9:41 AM To: flexcoders@yahoogroups.com Subject: Re: [flexcoders] any performance hit using "as"?   Hi Ted, maybe i misunderstand you, but your example works like expected for me. myArray = aCollection as Array; Since aCollection is not an Array, myArray is null afterwards. Cheers, Ralf. On 8/8/06, Ralf Bokelberg < ralf.bokelberg@gmail.com> wrote: Huh, i'd expect that myArray is null, because aCollection is not an Array. Cheers, Ralf.   On 8/8/06, Ted Patrick < [EMAIL PROTECTED]com> wrote: 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: [EMAIL PROTECTED]ups.com [mailto:[EMAIL PROTECTED]ups.com] On Behalf Of Pan Troglodytes Sent: Tuesday, August 08, 2006 8:11 AM To: [EMAIL PROTECTED]ups.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 -- Ralf Bokelberg < ralf.bokelberg@gmail.com> Flex & Flash Consultant based in Cologne/Germany -- Ralf Bokelberg <ralf.bokelberg@gmail.com> Flex & Flash Consultant based in Cologne/Germany __._,_.___ -- 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! 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