How to Use a Custom Method as a User-Defined Function (UDF)

Last reviewed: August 31, 1995
Article ID: Q136010
The information in this article applies to:
  • Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

This article gives details about how to create and use custom methods.

In FoxPro version 2.x, you can define procedures and functions in the cleanup code of FoxPro version 2.x screens. Forms in Visual FoxPro don't have an analogous place for defining procedures and functions, so you can:

  • Put cleanup code in a procedure file contained in the Project Manager, and issue a SET PROCEDURE TO statement.

    -or-

  • Create functions and procedures as custom methods of the form. These custom methods can then be referenced the same as any other method of the form or other object.

MORE INFORMATION

Custom methods can be coded to behave as functions behave; that is, they can return a value simply by ending the code definition with RETURN x where x is the name of a variable whose value is set in the method.

Custom methods should not begin with the PROCEDURE or FUNCTION command, which is normally used to indicate that a procedure or function is being defined, nor should they end with ENDPROC or ENDFUNC.

Step-by-Step Example

  1. Create a new form, and add two text boxes (Text1 and Text2) and two command buttons (Command1 and Command2).

  2. Add the Customer and Orders tables from the Testdata database to the data environment of the form.

  3. Set the ControlSource for the Text1 box to:

    customer.cust_id

  4. Set the ReadOnly property for the Text1 box to True (.T.).

  5. Leave the ControlSource property for the Text2 box blank.

  6. On the Form menu, click New Method. Enter Custcount as the name of the new method.

  7. Change the caption of the Command1 button to "Count orders," and enter the following code in the Click event procedure:

    nNum = thisform.custcount() thisform.text2.value = nNum thisform.refresh

  8. Change the caption of the Command2 button to Skip, and enter the following code in the Click event procedure:

    skip thisform.refresh

  9. Enter the following code for the Custcount custom method:

    x = 0 select orders go top count to x for orders.cust_id = thisform.text1.value select customer return x

When you click the Count orders button, the Custcount custom method is called to count how many orders exist in the Orders table for the current record in the Customer table. This number is returned to the Count orders button.


Additional reference words: 3.00 VFoxWin
KBCategory: kbprg kbcode
KBSubcategory: FxprgClassoop


THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: August 31, 1995
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.