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In this video, we'll learn about the c++11 final specifier.

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We can use the final specifier in two contexts.

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At the class level,

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the final specifier prevents a class from being derived from or subclassed.

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Sometimes frameworks have final classes that can't be subclassed.

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In some cases, this is done for better compiler optimization.

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Other times, it may be done to ensure that objects are copied safely without slicing.

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When used at the method or function level,

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the final specifier prevents the method from being overridden in derived classes.

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This can also be done for better compiler optimization.

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The syntax for using the final specifier at the class level is pretty simple.

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We simply add the final specifier after the class name when we declare it.

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In the first example, my class cannot be derived from.

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And in the second example, derived cannot be derived from.

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If you try to drive a class from these classes, the compiler will generate a compiler error.

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Now let's see the final specifier in the context of a virtual function.

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In this case, we have a simple class hierarchy with three classes: a b and c.

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The base class a declares the function do something as virtual.

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Class b is derived from a and it overrides do something

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but it also marks it as final.

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So do something can no longer be overridden further down in the hierarchy.

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Notice that if class c tries to override do something, the compiler generates an error.