Pointer to Self, comment?

Question

type 
    TMyClass = class 
    type 
    PMyClass = ^TMyClass; 
    TMyEvent = procedure(Sender: PmyClass) of object; 
    public 
    FTest: TMyEvent; 
    procedure Test; 
    end; 

procedure TMyClass.Test; 
begin 
    FTest(@Self); //error! 
end; 

Comment faire?

Answer 1

Que voulez-vous faire dans le monde? Bien sûr, vous ne pouvez pas appeler FTest puisque vous ne lui avez encore attribué aucun TMyEvent! Et sont PMyClass et TMyEvent vraiment censé être des parties de TMyClass?

Au moins cela fonctionne parfaitement:

type 
    PMyClass = ^TMyClass; 
    TMyClass = class; 

    TMyEvent = procedure(Sender: PMyClass) of object; 

    TMyClass = class 
    private 
    FEvent: TMyEvent; 
    FSomeValue: string; 
    public 
    property OnSomething: TMyEvent read FEvent write FEvent; 
    property SomeValue: string read FSomeValue write FSomeValue; 
    procedure Test; 
    end; 

    TSomeOtherClass = class 
    public 
    class procedure MyEvent(Sender: PMyClass); 
    end; 

... 

procedure TForm6.FormCreate(Sender: TObject); 
var 
    o: TMyClass; 
begin 

    o := TMyClass.Create; 
    o.SomeValue := 'This is a test.'; 
    o.OnSomething := TSomeOtherClass.MyEvent; 

    o.Test; 
end; 

{ TMyClass } 

procedure TMyClass.Test; 
begin 
    FEvent(@Self); 
end; 

{ TSomeOtherClass } 

class procedure TSomeOtherClass.MyEvent(Sender: PMyClass); 
begin 
    ShowMessage(TMyClass(Sender^).SomeValue); 
end; 

Bien sûr, vous pouvez aussi avoir les TMyEvent dans le même objet:

type 
    TMyClass = class 
    private type 
    PMyClass = ^TMyClass; 
    TMyEvent = procedure(Sender: PMyClass) of object; 
    private 
    FEvent: TMyEvent; 
    FSomeValue: string; 
    public 
    procedure TheEventHandler(Sender: PMyClass); 
    property OnSomething: TMyEvent read FEvent write FEvent; 
    property SomeValue: string read FSomeValue write FSomeValue; 
    procedure Test; 
    end; 

... 

procedure TForm6.FormCreate(Sender: TObject); 
var 
    o: TMyClass; 
begin 

    o := TMyClass.Create; 
    o.SomeValue := 'This is a test.'; 
    o.OnSomething := o.TheEventHandler; 

    o.Test; 
end; 

{ TMyClass } 

procedure TMyClass.Test; 
begin 
    FEvent(@Self); 
end; 

procedure TMyClass.TheEventHandler(Sender: PMyClass); 
begin 
    ShowMessage(TMyClass(Sender^).SomeValue); 
end;