在Delphi中枚举发布的属性和子属性

Question

如果之前询问过问题，表示歉意。我有一些组件的定义如下（如果它不对，请指导我，因为我是初学者）。我想要的是枚举派生组件的所有已发布属性，特别是子属性。我能够枚举属性的名称，但是，是否可以枚举发布的属性，我可以在执行程序期间访问元素（如在子属性中）？像getfirst/getnext一样一个一个地返回属性，直到最后？

type 
    TStringArray = array of string; 

    TGenericColumnDef = class(TPersistent) 
    private 
    fColumnName  : String; 
    fColumnNumber  : Integer; 
    fColumnDisplay  : string; 
    fColumnDescription : string; 
    fColumnDataType : integer; 
    fColumnEditorType : integer; 
// fMyEvent: TNotifyEvent; 
    protected 
    public 
    constructor create(AOwner: TComponent); virtual; 
    published 
    property ColumnName : String read fColumnName write fColumnName; 
    property ColumnNumber : integer read fColumnNumber write fColumnNumber; 
    //property MyEvent: TNotifyEvent read fMyEvent write fMyEvent; 
    end; 

TGenericAsset = class(Tcomponent) //TPersistent 
    private 
    { Private declarations } 
    fCiteID  : TGenericColumnDef; 
    fCiteType  : TGenericColumnDef; 
    fTitle   : TGenericColumnDef; 
    fAuthor  : TGenericColumnDef; 

    fPropertyCount : integer; 
    function GetPropertyCount : integer; 
    function GetNextPropertyIndex: integer; 
    property CountProperties  : integer read GetPropertyCount;// write fPropertyCount 
    protected 
    { Protected declarations } 
    FOwner: TObject; 
    public 
    { Public declarations } 
    constructor Create(AOwner: TComponent); override; 
    destructor destory ; virtual; 
    function GetColumnNameByColumnNumber(ColumnNumber : Integer) : String; 
    function GetColumnNames : TStringArray; 
// function GetFirst : TGenericColumnDef; 
    published 
    property CiteID : TGenericColumnDef read fCiteID write fCiteID; 
    property CiteType : TGenericColumnDef read fCiteType write fCiteType; 
    property Title : TGenericColumnDef read fTitle write fTitle; 
    property Author : TGenericColumnDef read fAuthor write fAuthor; 
    //property Nthproperty ......... 
end; 

//derived from TGenericAsset 
type 
TEditedBook = class(TGenericAsset) 
    private 
    protected 
    public 
    published 
    property CiteID : TGenericColumnDef read fCiteID write fCiteID; 
    property Title : TGenericColumnDef read fTitle write fTitle; 
    property Author : TGenericColumnDef read fAuthor write fAuthor; 
end; 

任何要点或准则（示例代码）的高度赞赏。 在此先感谢。

Answer 1

虽然它没有具体回答你的问题，但下面的代码（几年前由TeamB的Peter Peter博士捐赠给旧Borland Delphi新闻组）显示了如何使用RTTI克隆另一个组件。它显示如何获取（和设置）像其他对象，枚举类型等的子属性。它应该足以让你开始。我在代码中留下了Peter的注释，以及在函数下面以一些示例代码的形式使用它的示例。 （我也保存了他的代码格式和一些关键字的奇怪字母套。:)

// Unfortunately there is no easy way to "clone" a component in a way that 
// will also preserve event handlers. It can be done using run-time type 
// information and routines form the TypInfo unit, though. Try the following 
// routine. It is only superficially tested. 

Uses TypInfo; 

{-- CloneComponent ----------------------------------------------------} 
{: Make a copy of a component. 
@Param anObj is the component to copy 
@Param cloneChildren if true and anObj is a TWincontrol then all its 
    child controls will also be copied. 
@Param aParent is the parent to use if anObj is a TControl. 
@Returns the new object reference. It will have the same owner as anObj 
    and passes into the responsibility of the caller. 
@Precondition anObj <> nil 
@Desc The method creates a new object of the same class as anObj and then 
    uses TypInfo routines to copy all published properties. The logic used 
    for object properties is similar to what the form loading code uses: 
    if a property refers to a TComponent the component reference is copied. 
    If it refers to a TPersistent descendent the Assign method is used 
    to copy the objects contents. Currently TCollections do not receive 
    any special treatment, which may be necessary. <BR> 
    Note: the routine will not copy any objects *owned* by anObj, so it 
    cannot be used as is to clone a top-level container like a form, 
    frame, or datamodule. Those can be copied using WriteComponent and 
    ReadComponent with a TMemoryStream. 
}{ Created 12.4.2002 by P. Below 
-----------------------------------------------------------------------} 
Function CloneComponent(anObj: TComponent; 
         cloneChildren: Boolean = false; 
         aParent: TWinControl = nil): TComponent; 
Var 
    numProps, I : Integer; 
    props: PPropList; 
    PropInfo: PPropInfo; 
    obj, obj2: TObject; 
Begin { CloneComponent } 
    Assert(Assigned(anObj)); 
    Result := TComponentClass(anObj.ClassType).Create(anObj.Owner); 
    Try 
    numProps := GetPropList(anObj, props); 
    Try 
     For I := 0 To numProps - 1 Do Begin 
     PropInfo := props^[I]; 
     Case PropInfo^.PropType^.Kind Of 
      tkInteger, tkChar, tkEnumeration, tkSet, tkWChar: 
      SetOrdProp(Result, propinfo, 
         GetOrdProp(anObj, propinfo)); 
      tkFloat: 
      SetFloatProp(Result, propinfo, 
          GetFloatProp(anObj, propinfo)); 
      tkString, tkLString: 
      If not SameText(propinfo^.name, 'Name') Then 
       SetStrProp(Result, propinfo, 
          GetStrProp(anObj, propinfo)); 
      tkWString: 
      SetWideStrProp(Result, propinfo, 
          GetWideStrProp(anObj, propinfo)); 
      tkMethod: 
      SetMethodProp(Result, propinfo, 
          GetMethodProp(anObj, propinfo)); 
      tkInt64: 
      SetInt64Prop(Result, propinfo, 
          GetInt64Prop(anObj, propinfo)); 
      tkVariant: 
      SetVariantProp(Result, propinfo, 
          GetVariantProp(anObj, propinfo)); 
      tkInterface: 
      SetInterfaceProp(Result, propinfo, 
           GetInterfaceProp(anObj, propinfo)); 
      tkClass: Begin 
      obj := GetObjectProp(anObj, propinfo); 
      If Assigned(obj) Then Begin 
       If obj Is TComponent Then 
       SetObjectProp(Result, propinfo, obj) 
       Else If obj Is TPersistent Then Begin 
       obj2 := GetObjectProp(result, propinfo, TPersistent); 
       If Assigned(obj2) Then 
        TPersistent(obj2).Assign(TPersistent(obj)); 
       End; { If } 
      End; { If } 
      End; { Case tkClass } 
     Else 
      // we don't handle these property types: 
      // tkArray, tkRecord, tkDynArray 
     End; { Case } 
     End; { For } 
    Finally 
     FreeMem(props); 
    End; { Finally } 
    If anObj Is TControl Then 
     TControl(result).Parent := aParent; 
    If cloneChildren and (anObj Is TWinControl) Then 
     For i:= 0 To TWinControl(anObj).ControlCount-1 Do 
     CloneComponent(TWinControl(anObj).Controls[i], true, 
         TWinControl(Result)); 
    Except 
    Result.Free; 
    raise 
    End; { Except } 
End; { CloneComponent } 


procedure TForm1.GroupBox1MouseDown(Sender: TObject; Button: TMouseButton; 
    Shift: TShiftState; X, Y: Integer); 
begin 
    memo1.lines.add('Click on groupbox '+(sender as TComponent).Name); 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
Var 
    ctrl: TWinControl; 
begin 
    ctrl := CloneComponent(groupbox1, true, self) as TWincontrol; 
    With ctrl Do 
    SetBounds(left, top+height+8, width, height); 
    memo1.Lines.add(Format('Controlcount: %d', [ctrl.controlcount])); 
end;