Delphi TCollectionItem的子代中的事件
我编写了简单的代码(见下文):带有事件的Delphi TCollectionItem的子代中的事件,delphi,events,tcollectionitem,Delphi,Events,Tcollectionitem,我编写了简单的代码(见下文):带有事件的TCollectionItem的后代。但是,当我在object inspector中单击“OnDone事件”时,我会收到以下消息: “无法为未命名组件创建方法” 这个代码有什么问题 unit MainComponent2; interface uses Windows, SysUtils, Classes; type TMyField = class(TCollectionItem) private FName: string;
TCollectionItem
的后代。但是,当我在object inspector中单击“OnDone事件”时,我会收到以下消息:
“无法为未命名组件创建方法”
这个代码有什么问题
unit MainComponent2;
interface
uses Windows, SysUtils, Classes;
type
TMyField = class(TCollectionItem)
private
FName: string;
FOnDone: TNotifyEvent;
FText: string;
protected
function GetDisplayName : String; override;
public
constructor Create(ACollection: TCollection);override;
function GetNamePath: string;override;
published
property Name: string read FName write FName;
property Text: string read FText write FText;
property OnDone: TNotifyEvent read FOnDone write FOnDone;
end;
TMyFields = class(TOwnedCollection)
private
function GetItem(Index: Integer): TMyField;
procedure SetItem(Index: Integer; const Value: TMyField);
protected
procedure Update(Item: TmyField);reintroduce;
public
constructor Create(AOwner: TComponent);
function Add: TMyField;
function Insert(Index: Integer): TMyField;
property Items[Index: Integer]: TMyField read GetItem write SetItem; default;
end;
TMainComponent2 = class(TComponent)
private
FMyFields: TMyFields;
function GetItem(index: integer): TMyField;
procedure SetItem(index: integer; const Value: TMyField);
procedure SetMyFields(const Value: TMyFields);
public
constructor Create(AOwner: TComponent);override;
destructor Destroy;override;
property Items[index: integer]: TMyField read GetItem write SetItem;
published
property MyFields: TMyFields read FMyFields write SetMyFields;
end;
procedure Register;
implementation
{ TMainComponent2 }
constructor TMainComponent2.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FMyFields := TMyFields.Create(AOwner);
end;
destructor TMainComponent2.Destroy;
begin
FMyFields.Free;
inherited;
end;
function TMainComponent2.GetItem(index: integer): TMyField;
begin
result := FMyFields.Items[index] as TMyField;
end;
procedure TMainComponent2.SetItem(index: integer; const Value: TMyField);
begin
FMyFields.Items[index] := Value;
end;
procedure TMainComponent2.SetMyFields(const Value: TMyFields);
begin
FMyFields.Assign(Value);
end;
{ TMyField }
constructor TMyField.Create(ACollection: TCollection);
begin
inherited Create(ACollection);
FName := ClassName + IntToStr(ID);
end;
function TMyField.GetDisplayName: String;
begin
result := FName;
end;
function TMyField.GetNamePath: string;
begin
Result := Format('%s%d',['MyField', Index])
end;
{ TMyFields }
function TMyFields.Add: TMyField;
begin
result := (inherited Add) as TMyField;
end;
constructor TMyFields.Create(AOwner: TComponent);
begin
inherited Create(AOwner, TMyField);
end;
function TMyFields.GetItem(Index: Integer): TMyField;
begin
result := (inherited GetItem(Index)) as TMyField;
end;
function TMyFields.Insert(Index: Integer): TMyField;
begin
result := (inherited Insert(Index)) as TMyField;
end;
procedure TMyFields.SetItem(Index: Integer; const Value: TMyField);
begin
inherited SetItem(Index, Value);
end;
procedure TMyFields.Update(Item: TmyField);
begin
inherited Update(Item);
end;
procedure Register;
begin
RegisterComponents('MyComponents', [TMainComponent2]);
end;
end.
您忘记包含继承的
TMyField
的名称路径:
function TMyField.GetNamePath: string;
begin
Result := inherited GetNamePath + Format('MyField%d',[Index]);
end;
此外,您为MyFields
属性指定了错误的所有者。使用Self
而不是AOwner
AOwner
是您放置组件的表单
constructor TMainComponent2.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
FMyFields := TMyFields.Create(Self);
end;
B.t.w.为什么重新引入
TMyFields.Update
?这打破了继承链。尽可能使用覆盖
,或添加其他方法。谢谢!它起作用了。我使用reintroduce是因为当我使用重写编译器时,会说:“更新与以前的声明不同”。TOwnedCollection已更新(项:TCollectionItem)。我有更新(项目:TMyField)。您不必:TMyField
是一个t集合项目
。如果您需要将其视为<代码> TMyfield < /C> >,然后在