Closure
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A closure is like a bubble in JavaScript in that it acts like a separate self-contained global scope, and can contain variables, functions, and even entire JavaScript frameworks like jQuery. Closures can have both a private and public aspect, they're in the form of a function rather than an object, and are brought into existence by calling it, what's returned is the public interface. The content of the scope within the closures definition is private and exists for as long as the returned public interface exists.
The viewer onto the unified ontology intenernally maintains a closure for each node, and many of these nodes have a visible interface aspect in the form of an associated DOM element in the page. The unified ontology viewer also allows each node to be persistent by storing them in a peer-to-peer semantic network.
Examples
The following example illustrates a simple closure example. The variable foo is private and can only be accessed by functions in the same private scope, or by the functions returned in the public interface. An instance of the closure is created in the variable closure by being assigned the value returned by anonymously executing the declared function.
In the example above, the public function baz can access the private foo variable from it's local scope. The public interface also includes a variable bar which can be accessed publicly or via this from within the executing public interface functions. All of the items in both the private and the public scopes of the closure exist for the lifetime of the closure object.
In this next example, the closure is created without anything in the private scope, then there are two public functions which are called one after the other. The first stores a secret message in the private scope which the second displays. This shows that the private local scope of the functions remains intact after the function exits and is available to all the functions. It is not available outside the scope of the functions thought, any data which needs to be available outside the private scope of the closure needs to be prefixed with this.
