Q190539: HOWTO: Make Move or Resize Call Form’s THIS_ACCESS Method

Article: Q190539
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): 
Last Modified: 11-DEC-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SUMMARY
=======

Visual FoxPro 6.0 gives you the ability to attach events to properties. This is
accomplished using Access and Assign methods. These events will fire when a
property value is queried (that is, accessed) or set to a value (that is,
assigned). The THIS_ACCESS method is a special case that is fired whenever any
property of an object is queried or set. Normally, this method will be fired
only when properties are programmatically set or queried. This article describes
how to ensure the THIS_ACCESS method is called even if a property is implicitly
changed. An example of when you may want to do this would be when a form is
moved the form's Top property is changed.

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

This example demonstrates how THIS_ACCESS is not called by properties that are
implicitly changed.

1. Run the following code from a program (.prg) file:

        PUBLIC oform1

        oform1=NEWOBJECT("form1")
        oform1.SHOW
        RETURN

        DEFINE CLASS form1 AS FORM

           DOCREATE = .T.
           CAPTION = "Form1"
           NAME = "Form1"

           PROCEDURE this_access
              LPARAMETERS cMemberName
              ? cMemberName, TTOC(DATETIME())
              RETURN THIS
           ENDPROC

       ENDDEFINE

2. Resize or move the form with the mouse. Note that no output is echoed to the
  form.

This example shows how to make THIS_ACCESS be called when moving or resizing a
form by adding code to the form's Moved and Resize methods.

1. Run the following code from a program (.prg) file. Note the code added to the
  Moved and Resize methods.

        PUBLIC oform1

        oform1=NEWOBJECT("form1")
        oform1.SHOW
        RETURN

        DEFINE CLASS form1 AS FORM

           AUTOCENTER = .T.
           CAPTION = "Form1"
           NAME = "Form1"

           PROCEDURE this_access
              LPARAMETERS cMemberName
              ? cMemberName, TTOC(DATETIME())
              RETURN THIS
           ENDPROC

           PROC MOVED
              = THIS.TOP
              = THIS.LEFT
              ?
           ENDPROC

           PROC RESIZE
              = THIS.WIDTH
              = THIS.HEIGHT
              ?
           ENDPROC

        ENDDEFINE

2. Resize or move the form with the mouse. Note that the properties that are
  queried get echoed to the form.

REFERENCES
==========

Visual FoxPro Help file, "Access and Assign Methods" topic.
(c) Microsoft Corporation 1998, All Rights Reserved.
Contributions by Jim Saunders, Microsoft Corporation


Additional query words: kbVFp600 kbOOP

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbhowto

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