Flex MXML绑定与Actionscript绑定

Question

I'm hoping someone can explain what is going on under the hood when using MXML curly bindings.

For example, with itemrenderers:

If I bind some control via MXML to the data source such as:

text={data.myText}

Somehow these bindings seem to get automatically cleaned up.

However, if I bind using Actionscript when am I supposed to call unwatch()? How do I know when the itemRenderer is no longer being used?

How do the MXML bindings know when to un-bind?

Answer 1

With actionscript, you need to keep an instance of the watcher and clean it yourself. The curly braces is essentially a 'shortcut' that creates a lot of extra code to handle binding and clean up after itself (plus making sure it's not in a dependency loop). It's made for convenience while the actionscript version gives you more control, but creates more visible code.

I could go on, but Michael Labriola already has a great talk about the subject.