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问题:
I develop with FlashDevelop3 R2 and the Flex 3.3 SDK and there are many occasions where I must use the embed metadata tag as such:
[Embed(source="path/to/file")] private var Asset:Class;
I understand the above all well and good, and I am thankful it exists because I do not like to open the flash IDE too often.
When I am going through other authors classes lately, I have found an interesting metadata tag that I do not understand:
[Event(name="", type="")]
I have yet to see a situation where I require this, and furthermore I really just do not understand what it is for.
Thank in advance for your help.
Brian Hodge
blog.hodgedev.com hodgedev.com
回答1:
We use it for binding custom events to our custom MXML components. This tag allows you to reference it from MXML. See documentation:
[Event(name="enableChanged", type="flash.events.Event")]
class ModalText extends TextArea { ... }
<MyComp:ModalText enableChanged="handleEnableChangeEvent(event);"/>
The compiler will complain, however, if you try to refer to an event on an mxml tag that was not declared with an event metatag.
回答2:
These [Event(name, type)] declarations describe which events a class instance is likely to dispatch.
They are actually useful for code completion - for instance when you type: mySprite.addEventListener(, your code editor (Flex Builder or FlashDevelop) will display a meaningful list of events that this object can dispatch.
So you can add these declarations in your code and benefit from a richer code completion.
Also note that this works with custom Event classes (see FlashDevelop's new Event class template).
package mycomp { import flash.events.Event; public class MyEvent extends Event { public const SOME_EVENT:String = "someEvent"; // required Event type declarations } } package mycomp { [Event(name="someEvent", type="mycomp.MyEvent")] public class MyComp extends Sprite { } } package myproject { import mycomp.MyComp; public class MyProject { function MyProject() { var mc:MyComp = new MyComp(); mc.addEventLister( //completes: SOME_EVENT + Sprite events } } }
