Visitor Pattern

[himitsu]

Also doch das Gleiche.

Wenn es aufgeteilt werden soll, dann mußt man es auf eine gemeinsame Basis (Base) bringen.

Delphi-Quellcode:

unit BaseUnit;

interface

  type
    Visitor = class;
    Base = class
    public
      procedure Accept(v : Visitor); virtual; abstract;
      function Zeugs() : String; virtual; abstract;
    end;

    Visitor = class
    public
      procedure Visit(b : Base);
    end;

implementation

  { Visitor }
  procedure Visitor.Visit(b: Base);
  begin
    WriteLn(b.Zeugs());
  end;

  //...

end.

Delphi-Quellcode:

unit AUnit;

interface
  uses
    BaseUnit;

  type
    A = class(Base)
    public
      procedure Accept(v : Visitor); override;
      function Zeugs() : String; override;
    end;

implementation
  ...

Delphi-Quellcode:

unit BUnit;

interface
  uses
    BaseUnit;

  type
    B = class(Base)
    public
      procedure Accept(v : Visitor); override;
      function Zeugs() : String; override;
    end;

implementation
  ...