Chapter 10 Using VFP's Object- Oriented Tools - dFPUG-Portal

268 The Fundamentals of Visual FoxPro 6.0
Quick start to creating classes
You’re probably plenty full of theory by now. It’s time to actually start creating your own
classes. In this section, I’ll cover creating classes both from forms and from controls, and then
show you how to use both of them together.
Form classes
Creating your own form base class
1. Make sure that an active form base class hasn’t already been subclassed from Visual
FoxPro’s base classes.
2. Look in the Forms tab of the Tools, Options dialog. The Form Set and Form Template
Classes text boxes should be empty and the check boxes should be unchecked.
3. Create a form by issuing this command:
create form X
4. Modify the form to reflect how you want all of your forms to look and behave. Here
are some ideas:
• Change the caption to frmBase. This will act as a visual clue that the form you
just created has come from your own base class—not from Visual FoxPro. And
more importantly, the reverse. It’s pretty discouraging to create a form, drop a
bunch of controls on it and work with it for a while, only to discover that you’re
working on a Visual FoxPro base class form and not your own base class form.
• Drop a couple of Visual FoxPro buttons on the form – such as for Help and Done
(or Close, if you prefer.) Note that when you’re doing this for real, you’ll most
likely want to use controls that you’ve subclassed yourself, not Visual FoxPro’s
controls.
5. Select the File, Save As Class menu option. The Save As Class dialog opens as shown
in Figure 10.3. (Note that if you select Save As, you’ll just create another form that
references Visual FoxPro’s base class.)
6. Enter the name of the class—frmBase—in the Name text box, and the name of the
class library—BASECLASSES—in the File text box.
Note that Visual FoxPro will append the .VCX extension to BASECLASSES
automatically, because, after all, it knows you are creating a class.
You can also choose an existing class library by clicking the ellipsis button to the right
of the File text box, and then selecting a .VCX from the list that appears or navigating
to the .VCX you want.