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Destructor◄╣

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Destructor (VB Classic and C++/CLI Cross Reference Guide)

By Mike Prestwood

VB Classic versus C++/CLI: A side by side comparison between VB Classic and C++/CLI.

OOP Details

More object oriented (OO) stuff.

Destructor

[Other Languages]

General Info: Class Destructor

A special class method called when an object instance of a class is destroyed. With some languages they are called when the object instance goes out of scope, with some languages you specifically have to call the destructor in code to destroy the object, and others use a garbage collector to dispose of object instances at specific times.

Desctructors are commonly used to free the object instance but with languages that have a garbage collector object instances are disposed of when appropriate. Either way, destructors or their equivalent are commonly used to free up resources allocated in the class constructor.

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Are object instances freed with a garbage collector? Or, do you have to destroy object instances.

VB Classic:

When an object instance is destroyed, VB6 calls a special parameter-less sub named Class_Terminate. For example, when the variable falls out of scope. Since you cannot specify parameters for this sub, you also cannot overload it.

To explicitly destroy an object, use Set YourClass = nothing.

When an object instance is created from a class, VB6 calls a special sub called Class_Initialize.

More Info / Comment 1 certification question.

C++/CLI: "Finalizer" ~ClassName

Unlike standard C++, C++/CLI uses the .Net garbage collector to free managed object instances. Prism does not have nor need a true destructor.

In .Net, a finalizer is used to free non-managed objects such as a file or network resource. Because you don't know when the garbage collector will call your finalizer, Microsoft recommends you implement the IDisposable interface for non-managed resources and call it's Dispose() method at the appropriate time.

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