How to Implement a RELEASE Method

• Microsoft Visual FoxPro for Windows, version 3.0

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