>>All your forms should be based on the same form class. Data buffering, saving and un-doing changes, should be part of this class.
>
>How difficult is it to convert a form to use another base form?
That would depend on how it is programmed. But it is worth-while to go ahead and base your forms on classes.
Of course, if your forms are already based on classes, you can put the buffering in these classes.
>
>>Your class hierarchy might look like this (parent on left, children on the right):
>>
>>
>>Form
>>|
>>|--- cForm
>> |
>> |--- cDataForm
>> |--- other forms, including dialogs, reporting forms, ...
>>
>>
>>I.e., all your forms ultimately derive from a class cForm; forms that need to manipulate data derive from cDataForm.
>
>I think I need a bit more explanation on this part. Forms that don't use data, and those that do, are based from the one cForm? And if there are forms that use data, then those would be based from the cDataForm?
>
>>This data form typically has methods to:
>>
Check if there are changes to the current record (using GetFldState()
>>Save changes
>>Undo changes
>>Go to: next record, previous record, first record, last record
>>Ask for permission to go to another record or close form. This method - which might be called .CanChange() or something - will be invoked by .NextRecord(), .PreviousRecord(), etc. It will also be invoked in .QueryUnload(), if the user tries to close the form.
>
>Would you build navigation and add/edit/save/cancel buttons into this form, or just have methods available and design another class to do the visual stuff?
In any case, you should have methods. The reason is that the methods may be called from outside the forms, e.g. from the main menu, or from the main toolbar.
Whether you then add the buttons to the form is a minor esthetical detail. The button would just invoke the method, e.g. ThisForm.GoNext().
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