Gumbo introduces many new classes, some of which are re-implementations of existing Halo classes (and thus have the same name). In order to disambiguate between Halo and Gumbo, Gumbo classes are prefixed to avoid collisions. Gumbo components that have Halo equivalents, like Button, List and CheckBox, are now prefixed with the letters “Fx”. This means in MXML, a Gumbo Button would be instantiated via the <FXButton /> MXML tag, and a Halo Button would continue to be instantiated via the <Button /> MXML tag. Additionally, the new animation classes in Gumbo also follow the same prefix policy. A Gumbo resize effect is instantiated via the <FxResize /> MXML tag while a Halo resize effect is instantiated via the <Resize /> tag.
So what are they going to do for Flex 5, use “Fx2″?
Seriously, ActionScript has three* namespace constructs already, why introduce a fourth? Using prefixes is a hack to get namespaces in language that lacks them (like C or PHP), but packages were invented to solve exactly this problem.
In MXML it’s dead simple to use namespaces and prefixes to differentiate between different components with the same class name (e.g. <mx:Button> vs. <fx:Button>). The only place where it gets a bit messy is in ActionScript, but it seems to me that it is a fringe case when you want to juggle both a Halo and a Gumbo button or both a Halo and a Gumbo list in the same class (a Halo list and a Gumbo button, sure, but that wouldn’t cause a clash). I can see it happening, but not often enough to warrant such an ugly solution as this.
I remember when AIR was called Apollo and the
WindowedApplication class was called
ApolloApplication. This is the same kind of short-sightedness.
* Three namespace constructs: packages, namespaces and XML namespaces (which are different from packages since you can manually flatten a package structure with a manifest, e.g. the Flex namespace contains both classes from mx.core and mx.controls, and others).
Update: Adobe has decided to revert the decision of prefixing the new Gumbo classes. Good for everyone.