Virtual
From Free Pascal wiki
Jump to navigationJump to search
│
Deutsch (de) │
English (en) │
Back to Reserved words.
The modifier virtual:
- belongs to object-oriented programming;
- describes a virtual method.
A virtual method must also be implemented (programmed) in the class in which it was declared.
A virtual method can be overwritten in a derived class with the reserved word override.
If a virtual method is to be hidden, the class must be covered with the reserved word Reintroduce.
Example:
Type
TBody = class
private
dblHeight : double;
public
function volume : double; virtual; // This method can be in one of this class
// derived class can be hidden or overwritten
function surfaceArea double; virtual; // This method must be in one of this class
// derived class can be hidden or overwritten
end;