OVERRIDE

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgOverride
• Last revised: 2018-02-04

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Method attribute; specifies that a method must override a virtual

Syntax

Type typename Extends basename

...
Declare Sub|Function|Operator|Property|Destructor ... ( [parameterlist] ) [[ byref ] As datatype] Override
...

End Type

Description

In method declarations, Override can be used to indicate that this method is expected to override a virtual or abstract method from the base class. Then the compiler will show an error if the method does not override anything (only a non-static method can override a virtual or abstract method).

Use of Override is not mandatory to override a virtual or abstract method, it is highly recommended, as it will help prevent inadvertent errors (name/signature not matching).

Override can only be specified on the method declaration in the UDT block, but not on the method body, because it is just a compile-time check in the context of the inheritance hierarchy, and does not affect the method in any way.

Override is only recognized as a keyword at the end of member procedure declarations. It can still be used as identifier elsewhere.

Examples

start GeSHi

Type A Extends Object
    Declare Virtual Sub f1( )
    Declare Virtual Function f2( ) As Integer
End Type

Type B Extends A
    Declare Sub f1( ) Override
    Declare Function f2( ) As Integer Override
End Type

Sub A.f1( )
End Sub

Function A.f2( ) As Integer
    Function = 0
End Function

Sub B.f1( )
End Sub

Function B.f2( ) As Integer
    Function = 0
End Function

end GeSHi

Differences from QB

• New to FreeBASIC

See also

• Virtual, Abstract

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