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Q129281: How to Implement a RELEASE Method

Article: Q129281
Product(s): Microsoft FoxPro
Version(s): 3.00
Operating System(s): 
Keyword(s): kbcode
Last Modified: 25-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SUMMARY
=======

This article describes how to implement a RELEASE method in classes that do not
include a default RELEASE method.

MORE INFORMATION
================

When an object is instantiated, a variable, called an instance variable, is
created. Executing a form with a DO FORM command creates a Form object and an
instance variable. If the LINKED clause is included with the DO FORM command,
the form is associated with the instance variable, and releasing the instance
variable will also release the form.

By default, the LINKED clause is not included with the DO FORM. If the form is
not linked, you can release the variable while the form is active. The RELEASE
method is therefore necessary to the FORM or FORMSET classes to release forms
that do not have an associated instance variable.

Any object based on a class other than Form or FormSet is released when the
instance variable goes out of scope or is released. You can however implement a
custom RELEASE method that includes this command:

     RELEASE this && This command releases the current object

Sample Code
-----------

The following example code defines a toolbar that contains two command buttons.
One of the command buttons is a QUIT button. When the button is clicked, the
RELEASE method is called and the toolbar is released. Note that in this example,
the THISFORM keyword is used to generically reference the toolbar.

     PUBLIC oToolbar
     oToolbar=CREATEOBJECT('mytoolbar')
     oToolbar.show
     DEFINE CLASS mytoolbar AS TOOLBAR
     ADD OBJECT mycmd AS cmdmessage

     ADD OBJECT mycmdtwo AS cmdquit
     PROCEDURE RELEASE
     RELEASE THIS
     ENDPROC
     ENDDEFINE

     DEFINE CLASS cmdmessage AS COMMANDBUTTON
        Height=35
        Width=35
        Caption="Clients"
        PROCEDURE CLICK
         =MESSAGEBOX('To be implemented')
        ENDPROC
      ENDDEFINE
    *:
    *: Class: mycmdquit  BaseClass: COMMANDBUTTON
    *:

     DEFINE CLASS cmdquit AS COMMANDBUTTON
        Height=35
        Width=35
        CAPTION="Quit"
        PROCEDURE CLICK
           THISFORM.RELEASE
        ENDPROC
     ENDDEFINE

Additional query words: VFoxWin

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Keywords          : kbcode 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : 3.00

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