Quit/Close Callback

All Forms have a QUITCALL member that you can pass a standard callback string. This is executed whenever the user presses the Quit/Close icon (X) on the title bar of forms and the main application window.

If an open callback is used then it is called with the FORM object as its first parameter and ‘QUIT’ as its action string.

QUITCALL for MAIN Forms

For forms of type MAIN, the QUITCALL callback is executed, if present. This permits the user to terminate the application, and so the associated PML callback should prompt the user for confirmation.

If the user confirms the quit, then the callback should close down the application, and not return. If the user decides not to quit, then the callback should return an error to indicate the decision to F&M.

Use return error¼noalert if you want to avoid displaying an error alert. If the form has no QUIT callback, then the QUIT event will be ignored.

The following example shows a (global) PML function, that you could be use from all forms of type MAIN:

define function !!quitMain( )

 -- Sharable method Quit the application

 !str = !!Alert.Confirm('Are you sure you want to quit the application?')

 if( !str eq 'YES' ) then

  -- execute application termination command, which should not return

  finish

 else

  return error 3 |user chose not to QUIT| noalert

 endif

endfunction

This would be called from the form definition function body or from its constructor method as shown below:

Setup form !!myApplication MAIN

 . . .

 quitCall ‘!!quitMain( )’

 . . .

exit

define method .myApplication( )

 -- Constructor

 !this.quitCall = ‘!!quitMain( )’

 . . .

endmethod

QUITCALL for Other Forms

Essentially, if no QUIT callback is present, then the form is cancelled (hidden with reset of gadget values). If a QUIT callback is provided then you can prevent the default Cancel action by returning a PML error, but you must hide the form from your callback method (It is more efficient the use ‘!this.hide()’, rather than ‘hide !!myform‘ from your form methods).

Note: F&M does not display an alert for the returned error, it is merely for communication. You don’t need a QUIT callback if you just want to allow the form to be hidden. For DOCUMENT forms (MDI children) only, the callback must not display an alert as this will cause some gadgets to malfunction afterwards.