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//例1 成员变量
type
 TAncestor = class
Value: Integer;
 end;
 TDescendant = class（TAncestor）
Value: string;// hides the inherited Value field
 end;
var
 MyObject: TAncestor;
begin
 MyObject := TDescendant.Create;
 MyObject.Value := "Hello！" // error
（MyObject as TDescendant）.Value := "Hello！" // works！
end;
//例2 静态字段
type
TMyClass = class
public
class var// Introduce a block of class static fields.
Red: Integer;
Green: Integer;
Blue: Integer;
var// Ends the class var block.
InstanceField: Integer;
end;
//静态字段可以单独调用
TMyClass.Red := 1;
TMyClass.Green := 2;
TMyClass.Blue := 3;
//静态字段也可以通过对象实例调用
var
myObject: TMyClass;
myObject.Red := 1;
myObject.Green := 2;
myObject.Blue := 3;

//Static Methods
//例1
type
TFigure = class
procedure Draw;
end;
TRectangle = class（TFigure）
procedure Draw;
end;
var
Figure: TFigure;
Rectangle: TRectangle;
begin
Figure := TFigure.Create;
Figure.Draw;// calls TFigure.Draw
Figure.Destroy;
Figure := TRectangle.Create;
Figure.Draw;// calls TFigure.Draw
TRectangle（Figure）.Draw;// calls TRectangle.Draw
Figure.Destroy;
Rectangle := TRectangle.Create;
Rectangle.Draw;// calls TRectangle.Draw
Rectangle.Destroy;
end;
//虚方法和动态方法
type
TFigure = class
procedure Draw; virtual;
end;
TRectangle = class（TFigure）
procedure Draw; override;
end;
TEllipse = class（TFigure）
procedure Draw; override;
end;
var
 Figure: TFigure;
begin
 Figure := TRectangle.Create;
 Figure.Draw;// calls TRectangle.Draw
 Figure.Destroy;
 Figure := TEllipse.Create;
 Figure.Draw;// calls TEllipse.Draw
 Figure.Destroy;
 end;
//例2
type
 T1 = class（TObject）
procedure Act; virtual;
 end;
 T2 = class（T1）
procedure Act; // Act is redeclared, but not overridden
 end;
var
 SomeObject: T1;
begin
 SomeObject := T2.Create;
 SomeObject.Act;// calls T1.Act
end;
//类方法 Class Method
//Ordinary Class Methods
//The definition of a class method must begin with the reserved word class. For example,
type
TFigure = class
public
 class function Supports（Operation: string）: Boolean; virtual;
 class procedure GetInfo（var Info: TFigureInfo）; virtual;
end;
//The defining declaration of a class method must also begin with class. For example,
class procedure TFigure.GetInfo（var Info: TFigureInfo）;
begin
end;
//Class Static Methods
type
 TMyClass = class
 strict private
 class var
 FX: Integer;
 strict protected
 // Note: accessors for class properties must be declared class static.
 class function GetX: Integer; static;
 class procedure SetX（val: Integer）; static;
 public
 class property X: Integer read GetX write SetX;
 class procedure StatProc（s: String）; static;
 end;
//调用
TMyClass.X := 17;
TMyClass.StatProc（"Hello"）;