Friday, March 27, 2009

What’s the difference between ChangeWatcher.watch, and BindingUtils.bindProperty

Question :What’s the difference between ChangeWatcher.watch, and BindingUtils.bindProperty?
Answer :ChangeWatcher:
Acts like the watch on AS2. It watches a variable for changes and when something happens fires an
event. Make sure you call the canWatch to ensure that you can watch it!
There are 3 ways to specify the second parameter, the chain.
1. A String containing the name of a public bindable property of the host object.
ChangeWatcher.watch(this, "myvar", handler)
2. An Object in the form: { name: property name, access: function(host) { return host[name] } }.
The Object contains the name of a public bindable property, and a function which serves as a getter
for that property.
ChangeWatcher.watch(this, { name:"myvar", getter: function():String { return "something" }},
handler);
3. A non-empty Array containing any combination of the first two options. This represents a chain
of bindable properties accessible from the host. For example, to watch the property host.a.b.c, call
the method as: watch(host, ["a","b","c"]
BindingUtils.bindProperty
Works pretty much the same way as the watch, but instead of having to handle and event it allows
you to immediately bind two properties one-way.
The first two parameters are for the the target, the second parameters are the triggers.
BindingUtils.bindProperty( this, "va1", this, "var2");
Note : Make sure you add the flex framework.swc to your project Library Path to have access to the
mx.binding.util class.

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