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Com example in Mastering Delphi 5

Posted on 2001-06-30
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Last Modified: 2012-05-04
I am learning Delphi 5 com tech.
In the book Mastering Delphi5, there is a sample(page 698).

I tried the sample, but when the client side program run the intruction: Num1 := CreateComObject (Class_Number) as INumber; It got an error message: 'EIntfCastError: Interfacenot supported'.
I have registered the server, and I checked  the regstry, it looks right.

The following are the units' code:

/////////////Client Side ////////////////////
unit TestComF;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, Spin, NumIntf;

// redeclare the server GUID
const
  Class_Number: TGUID =
  '{2970D631-68F3-11D5-8384-8B6680C10D27}';

type
  TForm1 = class(TForm)
    SpinEdit1: TSpinEdit;
    Button1: TButton;
    Button2: TButton;
    SpinEdit2: TSpinEdit;
    Button3: TButton;
    Button4: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Button5: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
  private
    Num1, Num2 : INumber;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

uses
  ComObj;

procedure TForm1.FormCreate(Sender: TObject);
begin
  // create first object
  Num1 := CreateComObject (Class_Number) as INumber;
  Num1.SetValue (SpinEdit1.Value);
  Label1.Caption := 'Num1: ' + IntToStr (Num1.GetValue);
  Button1.Enabled := True;
  Button2.Enabled := True;

  // create second object
  Num2 := CreateComObject (Class_Number) as INumber;
  Label2.Caption := 'Num2: ' + IntToStr (Num2.GetValue);
  Button3.Enabled := True;
  Button4.Enabled := True;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  // change
  Num1.SetValue (SpinEdit1.Value);
  Label1.Caption := 'Num1: ' + IntToStr (Num1.GetValue);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  // increase
  Num1.Increase;
  Label1.Caption := 'Num1: ' + IntToStr (Num1.GetValue);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Num2.SetValue (SpinEdit2.Value);
  Label2.Caption := 'Num2: ' + IntToStr (Num2.GetValue);
end;


procedure TForm1.Button4Click(Sender: TObject);
begin
  Num2.Increase;
  Label2.Caption := 'Num2: ' + IntToStr (Num2.GetValue);
end;

procedure TForm1.Button5Click(Sender: TObject);
var
  Num3: INumber;
begin
  // create a new temporary COM object
  Num3 := CreateComObject (Class_Number) as INumber;
  Num3.SetValue (100);
  Num3.Increase;
  ShowMessage ('Num3: ' + IntToStr (Num3.GetValue));
end;

end.


///////////////Server side ////////////////////////////
library FirstCom;

uses
  ComServ,
  NumIntf in 'NumIntf.pas',
  NumServ in 'NumServ.pas',
  FirstCom_TLB in 'FirstCom_TLB.pas';

exports
  DllGetClassObject,
  DllCanUnloadNow,
  DllRegisterServer,
  DllUnregisterServer;

{$R *.TLB}

{$R *.RES}

begin
end.

unit NumIntf;

interface
  type
    INumber = interface
      ['{2970D630-68F3-11D5-8384-8B6680C10D27}']
      function GetValue: integer; stdcall;
      procedure Setvalue (new: integer); stdcall;
      procedure Increase; stdcall;
    end;

implementation

end.


unit NumServ;

interface

uses
  Windows, ActiveX, Classes, ComObj, NumIntf;

type
  TNumber = class(TComObject, INumber)
  private
    fValue : integer;
  public
    function GetValue: integer; virtual; stdcall;
    procedure Setvalue (new: integer); virtual; stdcall;
    procedure Increase; virtual; stdcall;
    procedure Initialize; override;
    destructor Destroy; override;
  end;

const
  Class_Number: TGUID = '{2970D631-68F3-11D5-8384-8B6680C10D27}';

implementation

uses ComServ;

{ TNumber }

destructor TNumber.Destroy;
begin
  inherited;
  MessageBox (0, 'Object Destroyed',
    'TDLLNumber', mb_OK); // API call
end;

function TNumber.GetValue: integer;
begin
  Result := fValue;
end;

procedure TNumber.Increase;
begin
  Inc (fValue);
end;

procedure TNumber.Initialize;
begin
  inherited;
  fValue := 10;
end;

procedure TNumber.Setvalue(new: integer);
begin
  fValue := New;
end;

initialization
  TComObjectFactory.Create(ComServer, TNumber, Class_Number,
    'Number', 'Number server', ciMultiInstance, tmApartment);
end.


Peter
0
Comment
Question by:petershaw8
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3 Comments
 
LVL 13

Expert Comment

by:Epsylon
ID: 6242157
It works fine here. Try reregistering it using:

Run menu > Register ActiveX Server
0
 
LVL 13

Accepted Solution

by:
Epsylon earned 400 total points
ID: 6242194
Btw, do you have the lastest Delphi 5 patches installed?
0
 

Author Comment

by:petershaw8
ID: 6244410
Hi Epsylon,
I installed Delphi 5 patche files.
I tried to reregister it (Run menu > Register ActiveX Server)and used regsvr32.exe in windows\system as well. But it still doesn't work.


Peter
0

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