如何重载ClientDataSet的BeforePost事件？？？？

[monglihong]

我设计了一个类
封装了一个ClientDataSet、DataSetProvider等

现在我想重载ClientDataSet的BeforePost事件
代码该如何写

[RaulWhite]

可否这样写呢
增加
　FBeforePost: TDataSetNotifyEvent;
property BeforePost: TDataSetNotifyEvent read FBeforePost write FBeforePost;
在Create事件里
FClientDataSet:=TClientDataSet.Create(nil);
FCliendDataSet.BeforePost := BeforePost;
那么TClientDataSet的BeforePost事件就是你自己类的BeforePost事件了，你想怎么写都行了

这里不需要用到重载，而是为TClientDataSet的BeforePost事件指定事件处理过程。这个处理过程就是你自己类的过程了。当TClientDataSet的BeforePost事件发生里，自动会调用你自己类的FBeforePost过程

[monglihong]

现附上源码
请各位仁兄仁姐指教：

unit Uni_ucctMid;

interface

uses
SysUtils, Classes, Controls, Grids, DBGridEh,DB, ADODB,
DBClient, Provider;

type
TMidcom = class(TObject)
private
{ Private declarations }

FAdoConn:TADOConnection; //ADO连接
FQueryTemp:TADOQuery; //临时查询
FQueryDisp:TADOQuery; //显示查询
FDataSetProvider:TDataSetProvider; //客户端连接
FClientDataSet:TClientDataSet; //客户端数据集
FDataSource: TDataSource; //数据源
FRowUpdate:Boolean; //数据更新类型
FTableName:String; //操作表名


function GetConn: String; //取连接
function GetTableName: String; //取操作表名
function GetDataSource: TDataSource; //取数据源
procedure SetConn(const Value: String); //设置连接
procedure SetTabName(const Value: String);
function GetRowUpdate: Boolean;
procedure SetRowUpdate(const Value: Boolean); //设置操作表名

protected
{ Protected declarations }
public
{ Public declarations }
constructor Create(AOwner: TComponent); //override;
destructor Destroy; override;

function Open():Boolean;
function ApplyUpdates():Boolean;

property ConnString: String read GetConn write SetConn;
property TableName: String read GetTableName write SetTabName;
property DataSource:TDataSource read GetDataSource;
property RowUpdate:Boolean read GetRowUpdate write SetRowUpdate;

published
{ Published declarations }
end;


implementation

{TMidcom}


//******************************************************************************
//类的构造函数
//******************************************************************************
constructor TMidcom.Create(AOwner: TComponent);
begin //类创建
FAdoConn:=TADOConnection.Create(nil); //动态创建各对象
FQueryTemp:=TADOQuery.Create(nil);
FQueryDisp:=TADOQuery.Create(nil);
FDataSetProvider:=TDataSetProvider.Create(nil);
FClientDataSet:=TClientDataSet.Create(nil);
FDataSource:=TDataSource.Create(nil);

FAdoConn.LoginPrompt:=False; //
FQueryTemp.Connection:=FAdoConn;
FQueryDisp.Connection:=FAdoConn;
FDataSetProvider.DataSet:=FQueryDisp;
FClientDataSet.SetProvider(FDataSetProvider);
FDataSource.DataSet:=FClientDataSet;
FRowUpdate:=False;
end;

//******************************************************************************
//析构函数
//******************************************************************************
destructor TMidcom.Destroy;
begin //类释放
FDataSource.Free;
FClientDataSet.Free;
FDataSetProvider.Free;
FQueryTemp.Free;
FQueryDisp.Free;
FAdoConn.Free;
inherited;
end;

function TMidcom.GetConn: String;
begin //读取连接字符串
Result:=FAdoConn.ConnectionString;
end;

function TMidcom.GetTableName: String;
begin //读取操作表名
Result:=FTableName;
end;

procedure TMidcom.SetConn(const Value: String);
begin //设置连接字符串
try
FAdoConn.Connected:=False;
FAdoConn.ConnectionString:=Value;
FAdoConn.Connected:=True;
except
end;
end;

procedure TMidcom.SetTabName(const Value: String);
begin //设置操作表名
FTableName:=Value;
end;

//******************************************************************************
//浏览数据
//******************************************************************************
function TMidcom.Open: Boolean;
var strTable:String;
i:Integer;
NewField:TStringField;
begin
try
strTable:=TableName;
FQueryDisp.Active:=False;
FQueryDisp.SQL.Text:='select * from '+strTable;
FQueryDisp.Active:=True;
FClientDataSet.Active:=true;

strTable:=FTableName;
If FAdoConn.Connected=False then Result:=False;
FQueryTemp.Active:=false;
FQueryTemp.SQL.Text:='select * from ZDXXB where strTable='''+strTable+'''';
FQueryTemp.Active:=True;
if FQueryTemp.RecordCount>0 then
begin
while not FQueryTemp.Eof do
begin
for i:=0 to FClientDataSet.Fields.Count-1 do
if FClientDataSet.Fields[i].FieldName=FQueryTemp.fieldbyname('strEName').AsString then
begin
FClientDataSet.Fields[i].DisplayWidth:=FQueryTemp.fieldbyname('IntDLong').AsInteger;
FClientDataSet.Fields[i].DisplayLabel:=FQueryTemp.fieldbyname('strCName').AsString;
Break;
end;
FQueryTemp.Next;
end;
end;
Result:=True;
except
Result:=False;
end;
end;

function TMidcom.GetDataSource: TDataSource;
begin //读取数据源
Result:=FDataSource;
end;


function TMidcom.GetRowUpdate: Boolean;
begin //读取数据更新方式
Result:=FRowUpdate;
end;

procedure TMidcom.SetRowUpdate(const Value: Boolean);
begin //数据数据更新方式
FRowUpdate:=Value;
end;

function TMidcom.ApplyUpdates: Boolean;
begin //批量更新数据源
try
FClientDataSet.ApplyUpdates(-1);
Result:=True;
except
Result:=False;
end;
end;

//******************************************************************************
//问题在这里,基类并不是TClientDataSet
//如何重载TClientDataSet的BeforePost事件
//对每一行更新的数据进行安全性、完整性验证
//******************************************************************************
end.