Wrapping the call to MessageBox()
The MessageBox() function in Visual FoxPro lets you display a standard Windows
dialog to get a Yes/No answer from the user. The dialog is reliable and familiar
but the call to this function can be a bit verbose:
("Are you sure",
MB_ICONQUESTION + MB_YESNO,
"Delete record") = IDYES ...
This call then gives you a return value of 6 or 7 so you need to
write further code to determine whether the user said 'Yes' or 'No'. The
task is not difficult but the extra parameters do make the code look messy.
You can make life a lot easier by writing a function to wrap the MessageBox
call. We use a function named "Confirm" which takes the text and title
as parameters and converts the numeric return from MessageBox into the
True or False values .T. or .F..
The body of the function is very simple:
Lparameter tcText, tcTitle
lnResponse = Messagebox(tcText, ;
MB_ICONQUESTION + MB_YESNO, ;
Return lnResponse = IDYES
The code to use this function is much easier to write than the call to
the MessageBox function because you can embed it into an
Confirm("Are you sure", "Delete record") ...
A more sophisticated function
Our basic Confirm() function has grown more sophisticated over
the years. The second parameter is now optional and the function
uses PCount() to count the
number of parameters received. If there is only one parameter then
it defaults to using the screen caption as the title for the
MessageBox dialog. This makes calling the function even simpler.
An additional bonus in our work is that we have no longer have to
remember the different calling conventions for the FoxPro and
Both languages use the standard Windows dialog
and both require a parameter of 36 and will return 6 or 7 as the result.
The difference is that Access calls it with the
function rather than
and has constants named
in Visual FoxPro. We've now got a
"Confirm()" function written in both languages so we don't have to worry
about these annoying differences any more.