我正在编写一个 TCustomDBGrid 后代组件,该组件需要访问 protected 属性Options( TGridOptions ),它是 TCustomGrid 对象的父类(TCustomDBGrid)的一部分。问题是存在的属性与TCustomDBGrid类中重新引入的属性相同,但具有另一种类型(TDBGridOptions)。

检查简化此声明

 TCustomGrid=  = class(TCustomControl)
 protected
  //I need to access this property
  property Options: TGridOptions read FOptions write SetOptions
      default [goFixedVertLine, goFixedHorzLine, goVertLine, goHorzLine,
      goRangeSelect];
 end;

  TCustomDBGrid = class(TCustomGrid)
  protected
    //a property with the same name is reintroduced in this class
    property Options: TDBGridOptions read FOptions write SetOptions
      default [dgEditing, dgTitles, dgIndicator, dgColumnResize, dgColLines,
      dgRowLines, dgTabs, dgConfirmDelete, dgCancelOnExit, dgTitleClick, dgTitleHotTrack];
  end;


  TDBGridEx = class(TCustomDBGrid)
  protected
    //inside of this method I need to access the property TCustomGrid.Options
    procedure FastDraw(ACol, ARow: Longint; ARect: TRect; AState: TGridDrawState);
  end;

我想出了如何使用cracker类访问此属性。
type
  TCustomGridClass=class(TCustomGrid);

{ TDBGridEx }
procedure TDBGridEx.FastDraw(ACol, ARow: Integer; ARect: TRect; AState: TGridDrawState);
var
 LOptions: TGridOptions;
 LRect : TRect;
begin
  ......
  LOptions := TCustomGridClass(Self).Options; //works fine
  LRect := ARect;
  if not (goFixedVertLine in LOptions) then
    Inc(LRect.Right);
  if not (goFixedHorzLine in LOptions) then
    Inc(LRect.Bottom);
  .....
end;

但是仅出于好奇我想知道是否存在其他解决方法或更好的解决方案。

最佳答案

这是使用class helpers的另一种解决方法。它不如您的黑客好,但可以使用。

type
  TCustomGridHelper = class helper for TCustomGrid
    function GetGridOptions: TGridOptions;
  end;

function TCustomGridHelper.GetGridOptions: TGridOptions;
begin
  Result := Self.Options;
end;

procedure TDBGridEx.FastDraw(ACol, ARow: Integer; ARect: TRect;
  AState: TGridDrawState);
var
 LOptions: TGridOptions;
 LRect : TRect;
begin
  ...
  LOptions := Self.GetGridOptions; //works fine
  ...
end;

09-10 03:04
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