Flex - The Wizard behind the Curtain
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Published
Tuesday, November 29, 2005
at
2:38 AM
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Flex MXML is translated into an ActionScript Class before it is compiled into SWF. The easiest way to learn the deeper side of Flex is to modify your installation to keep generated actionscript. You will learn more about Flex than you ever wanted to know.
I learn by doing and this feature of Flex has allowed me to learn the deeper side of Flex. It allows you to see how Flex application internals work and allows you to explore the deeper APIs within the Flex Framework. Lets face it, it is one thing to write MXML, but quite another to bend Flex to work they way you want.
Exploring Flex 101 - How to turn on "keep-generated-as":
1. Locate this file:
{FLEX INSTALL}/WEB-INF/flex/flex-config.xml
2. Locate the XML tag "keep-generated-as" and modify the value to 'true'
3. Restart Flex
Now whenever an MXML application is compiled, the generated AS file will remain on the file system like so:
MyApp.mxml
MyApp-generated.as
Open the generated AS file and be prepared for a jolt of development reality. It is so nice to locate "The wizard behind the curtain".
Cheers,
Ted ;)
Actually, along these lines if you were to open the .SWD (ie put FLEX debugging on) you'll see the original source code used - for those of you who want to know how certain controls look under the hood).
Scott,
Ahhhh good one Scott. So this must explain your killer Flex skinning ability! Seriously, I have never seen anyone skin Flex like Scott can. He wrote a WinAmp Flex Theme that is almost unbelievable in quality.
Cheers Scott!
Ted ;)
Thanks for the tip Ted! Quick Q: I'm working with Flex Builder 2 Alpha 1, and I haven't been able to find the MyApp-generated.as file anywhere. I checked flex-config.xml (which was in "C:\Program Files\Macromedia\Flex Builder 2 Alpha 1\Flex Framework 2 Alpha 1\frameworks") and the key "keep-generated-actionscript" is already set to "true". I then built an app - tried both "run" and "debug" - but couldn't find the generated AS file anywhere.
Do you know if this tip is applicable to Flex 2?
Thanks!
Avi
Avi,
In Flex Builder 2 Alpha 1, the compiler setting seems to be broken. We will have to wait until a later release of Flex Builder 2 Beta until this feature is functioning.
Plus its early on Flex 2 and the generated AS will most likely change wildly before release as features are added and optimizations made.
I expect that keep-generated-as will make the final release of Flex Builder 2.0 given it has shiped with all prior Flex products and is avialable with CF7 too!
Cheers,
ted ;)
I would be interested in seeing some skinning example screen shots just to motivate me ;) Any change for this?
Jason Hawryluk
Do you know if there's any way to set the path for the generated .as files?
With a big project the generated .as files gets a little bit unwieldy.
Actually you do have a chance to see a generated as code in Flex2. You shoud feed -keep-generated-actionscript directly to mxml compiler, ie "c:\Program Files\Macromedia\Flex Builder 2 Alpha 1\Flex Framework 2 Alpha 1\bin\mxmlc.exe -keep-generated-actionscript your.mxml".
But well, you'll hardly get lucky when you see the code.