FILE: Programmatically Retrieve the Members of a DLL Class

Last reviewed: August 26, 1997
Article ID: Q172988
The information in this article applies to:
  • Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0

SUMMARY

This article shows you how to programmatically retrieve the class names and members of a dll or ActiveX file that contains a type library. You can get this information by using the Object Browser in Visual Basic or you can programmatically retrieve this information. The sample program uses an unsupported file Tlbinf32.dll to retrieve some of the type library information, but is not a complete substitute for the Object Browser.

NOTE: The file Tlbinf32.dll is not supported by Microsoft Technical Support either electronically or via telephone. This file is subject to change without notice.

A Visual Basic project that demonstrates how to use this file to get the class names and members from a dll or ActiveX controls is available for download from the Microsoft Software Library:

 ~ Clsnmmbr.exe (size: 20335 bytes) 

For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

The Object Browser in Visual Basic shows you the collections and member names of a dll class. You may want to develop an add-in for use in other development environments that has the same functionality as the object browser and to add some automation capabilities. This sample shows you how to retrieve this information programmatically by using the file tlbinf32.dll. This file is stored in the OS\System directory of your installation disk and is copied to your computer's system folder during the Visual Basic installation.

After downloading and running the self-extracting file, the following files are extracted to your hard drive:

  • From1.frm (4K)
  • Form1.frx (1K)
  • Project1.vbp (1K)
  • Project1.vbw (1K)
  • Readme.txt

When you run the project in Visual Basic by pressing the F5 key, click the Choose file button to select a dll or ActiveX file. If the file contains a type library, the class names and members are displayed in the list box.

You can duplicate this project by completing the steps shown in the following section.

Step-by-Step Example

  1. Start Visual Basic and chose Standard Exe or, if Visual Basic is already running, choose New Project from the File menu.

  2. Set a reference to the file Tlbinf32.dll by completing the following steps:

    a. From the Project menu, click References. The References dialog box

          is displayed.
    

    b. From the References dialog box, click Browse.

    c. From your Windows system directory, select the file Tlbinf32.dll.

  3. Add the following controls to the Form1 form and set the indicated properties:

       Control               Property Name             Property Setting
       ----------------------------------------------------------------
       Command Button        Name                      Command1
                             Caption                   Choose File
                             Height                    495
                             Left                      4800
                             TabIndex                  3
                             Top                       720
                             Width                     1815
    
       Command Button        Name                      Command2
                             Caption                   End
                             Height                    495
                             Left                      4800
                             TabIndex                  4
                             Top                       1320
                             Width                     1815
    
       Text Box              Name                      Text1
                             Height                    375
                             Left                      1080
                             TabIndex                  1
                             Top                       120
                             Width                     5535
    
       List Box              Name                      List1
                             Height                    2205
                             Left                      120
                             Top                       720
                             Width                     4455
    
       Common Dialog         Name                      CommonDialog1
    
       Label                 Name                      Label1
                             Caption                   Selected DLL
                             Height                    375
                             Left                      0
                             TabIndex                  2
                             Top                       120
                             Width                     1095
    
    

  4. Copy and paste the following code to the Code window of the Form1 form.

          Private Sub Form_Load()
    
              strFilter = "DLL Files (*.dll)|*.dll|"
              strFilter = strFilter & "OCX Files (*.ocx)|*.ocx|"
              strFilter = strFilter & "All Files (*.*)|*.*"
              CommonDialog1.Filter = strFilter
          End Sub
    
          Private Sub Command1_Click()
              Dim x As TypeLibInfo
              Dim y As CoClasses
              Dim z As Interfaces
              Dim w As Members
              Dim u As MemberInfo
              Dim i As Integer, j As Integer, n As Integer, k As Integer
              Dim strFilter As String
              Dim strName As String, strMembers As String
    
              On Error Resume Next
              CommonDialog1.ShowOpen
              List1.Clear
              Text1.Text = ""
    
              'Program ends if you click the Cancel button in the
              'file open dialog box
              If CommonDialog1.Flags = 0 Then
                  End
              End If
    
              'Get information from type library
              Set x = TypeLibInfoFromFile(CommonDialog1.filename)
              Set y = x.CoClasses
    
              'Show Type Library information in the List box
              For i = 1 To y.Count
                  If i <> 1 Then
                      strName = ""
                      List1.AddItem strName
                  End If
                  strName = "Class Name: " & y.Item(i).Name
                  List1.AddItem strName
                  Set z = y.Item(i).Interfaces
                  For n = 1 To z.Count
                      Set w = z.Item(n).Members
                      For k = 1 To w.Count
                          Set u = w.Item(k)
                          strMembers = "      Member: " & u.Name
                          List1.AddItem strMembers
                      Next
                  Next
              Next
              Set z = Nothing
              Set y = Nothing
              Set x = Nothing
              Set w = Nothing
    
              'Display filename in the text box
              Text1.Text = CommonDialog1.filename
    
              'If the file does not contain type library information
              'then display this error message.
              If Err.Number = 91 Then
                  Dim strMsgTitle As String, strMsgError As String
                  Dim intResponse
                  strMsgTitle = "No Type Library"
                  strMsgError = "You chose a file without a type library. "
                  strMsgError = strMsgError & "Choose another file."
                  Err.Clear
                  intResponse = MsgBox(strMsgError, vbOKCancel, strMsgTitle)
    
                  If intResponse = vbOK Then
                      Command1_Click
                  End If
    
              End If
    
          End Sub
    
          Private Sub Command2_Click()
              End
          End Sub
    
    

  5. Press the F5 key to run the program. Select a .dll or an ActiveX control file. If the file contains a type library, the class names and members are displayed in the list box.

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Arsenio Locsin, Microsoft Corporation
Keywords          : vb5all VBKBWinAPI kbsample
Version           : WINDOWS:5.0
Platform          : WINDOWS
Solution Type     : kbfile


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Last reviewed: August 26, 1997
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