Keyword Final - leonard-thieu/monkey GitHub Wiki

Declares that a class may not be extended or that a method may not be overridden.

Syntax

  Class Identifier [ < Parameters > ] [ Extends Class ] [ Implements Interfaces ] [ Final ]    Declarations...   End [ Class ]

  Method Identifier : ReturnType ( Parameters ) [ Property ] [ Abstract ] [ Final ]    Statements...   End [ Method ]

Description

The Final modifier can be used in two contexts:

• Classes - the Final keyword at the end of a Class statement declares that the class may not be extended by other classes;
• Methods - the Final keyword at the end of a Method statement declares that a method may not be overridden (in an extended version of a non-Final class).

The examples below should help to clarify these cases.

See also

• Class
• Method
• Classes

Examples

In this case, we try to extend the Dog class to create a Doberman class; however, this is forbidden due to the Final keyword in the Class statement.

This example will intentionally generate an error.

' Runnable example

Class Dog Final

    Method Bark ()
        Print "Woof!"
    End

End

Class Doberman Extends Dog

    ' Think I'll make my own Dog!

End

Function Main ()

    Local d:Doberman = New Doberman

End

---

In the example below, Dog can be extended (no Final modifier); however, we have stated that the Bark method may not be overridden, again, using the Final modifier.

This example will intentionally generate an error.

' Runnable example

Class Dog

    Method Bark () Final
        Print "Woof!"
    End

End

Class Doberman Extends Dog

    Method Bark ()
        Print "RRGGGHHHRRRGHGHWWRRRRR!!!"
    End

End

Function Main ()

    Local d:Doberman = New Doberman
    d.Bark

End

Note that in both cases, no error will be flagged unless (in the first example) you try to create a Doberman, or (in the second example) call the erroneously overridden method.