I like. On Dec 5, 2016, at 8:49 PM, Alex Harui <aha...@adobe.com> wrote:
> Hi, > > I just pushed changes to allow certain kinds of overrides in SWF that > normally aren't possible. The reasoning behind doing this is to allow us > to have a library that extends SWF classes like Sprite but hide the flash > APIs. > > For example, in Sprite, the parent property is defined as a > flash.display.DisplayObjectContainer. In FlexJS, we would much rather use > a non-Flash API like org.apache.flex.core.IParent, so a parent can be > platform-agnostic. Similarly, the dispatchEvent API takes a > flash.events.Event and it would be better to have it take an > org.apache.flex.events.Event, or maybe an > org.apache.flex.events.IFlexJSEvent. > > So, in our base classes, we would want to write: > > override public function get parent():IParent > > And > > override public function > dispatchEvent(event:org.apache.flex.events.Event):Boolean > > But not only would the SWF compiler not allow that, the Flash runtime > checks the type of any override at runtime and reports an error if there > isn't a match (and such an issue would not be caught by the JS runtime). > > So to get this all to work, the compiler needs to know that certain > type-mismatches are allowed, and also to restore the type to the original > type in the SWF. To do so, I taught the compiler to look for a > SWFOverride metadata that provides the original types for parameters or > return values. When the compiler sees a mismatch, it checks for metadata > allowing the mismatch. And when writing out the SWF, it also checks for > the metadata and replaces the types in the ABC traits. So far, in minimal > testing, it seems to work. > > Next up, after fixing a bunch of bugs in the queue, is to work on having > the compiler generate both SWF and JS output in a single run. Then with > proper overriding of various Flash APIs, we should be able to provide a > more efficient way for FlexJS developers to see any conflicts with > underlying platform implementations without having to wrap every > implementation. > > Later, > -Alex >
