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

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