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https://issues.apache.org/jira/browse/FLEX-34897?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Josh Tynjala closed FLEX-34897.
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> Scope is wrong when calling member function from a variable reference
> ---------------------------------------------------------------------
>
> Key: FLEX-34897
> URL: https://issues.apache.org/jira/browse/FLEX-34897
> Project: Apache Flex
> Issue Type: Bug
> Components: FalconJX
> Affects Versions: Apache FalconJX 0.5.0
> Reporter: Josh Tynjala
> Assignee: Alex Harui
> Fix For: Apache FalconJX 0.5.0
>
>
> In Flash Player, when you save a reference to a member function in a
> variable, you can call the function reference, and "this" will still be bound
> to the instance where it came from.
> public class Test
> {
> public function Test()
> {
> this.func();
> var func:Function = this.func;
> func();
> }
> private function func():void
> {
> trace(this); //in Flash, "this" will always be an instance of Test
> }
> }
> Basically, in the code above, the two calls to func() will behave the same in
> Flash Player. However, in the current implementation of the transpiler, that
> behavior is lost. When the variable reference to the function is called,
> "this" ends up referring to the global window object instead.
> JavaScript function objects have a bind() function that let's you set what
> "this" will refer to when the function is called:
> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind
> After modifying my code to use bind(), the two calls to func() will behave
> the same:
> public function Test()
> {
> this["func"] = this.func.bind(this);
> this.func();
> var func:Function = this.func;
> func();
> }
> Would it be possible for the transpiler to automatically bind all member
> functions to the correct scope to preserve the behavior that AS3 developers
> expect?
> Event listeners are the typical use case where you'd pass a reference to a
> member function somewhere else where a reference needs to be saved in a
> variable. AS3 in Flash Player makes this easy by automatically binding all
> member functions to the instance. JavaScript usually requires some manual
> intervention to get event listeners to be called with the right scope.
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