VFP 9 SP 1
I ran across this oddment today:
Consider an SCX form containing a textbox, a command button, and a method
called ProcessIt(). If you press the command button, THISFORM.ProcessIt()
is called.
ProcessIt()
LOCAL thelastname
thelastname = ""
IF NOT EMPTY(THISFORM.Text1.Value)
thelastname = ALLTRIM(THISFORM.Text1.Value)
IF [?] $ thelastname OR [/] $ thelastname ;
OR [\] $ thelastname OR [(] $ thelastname ;
OR [)] && Obvious error here (unless you're tired and didn't
catch it...)
MESSAGEBOX("Invalid input.")
ENDIF
ENDIF
* Just for grins...
IF ")"
MESSAGEBOX("Invalid input.")
ENDIF
If you type this code into the method and save the form, the auto-compile
feature won't complain. But this is obviously bad syntax, as you can find
out if you try to run the code in the command window. You'll get a data
type mismatch error.
I'm used to auto-compile not detecting errors in .prg-based code unless I
go through the contortions necessary to invoke Intellisense. I've come to
expect better behavior in SCX and VCX methods though.
Still, I was aware that even in an SCX form the auto-compile can't detect
data-type mismatches involving the unambiguously-defined contents of
variables--though that surprises me since the command window will do so.
But I didn't realize the auto-compile can't detect a data-type mismatch on
a comparison expression involving a string literal.
Nor will the full compile of an executable containing this error.
This little oddment cost me three hours of debugging. It's weird enough
that it caused the obliteration of several levels of stack trace in my
executable at run time. The stack trace data from ASTACKINFO() didn't show
up in my error handler's log output until it was well past the point of the
error and into my shutdown routine. Took me forever to find the source of
the error.
Any comments?
Thanks.
Ken Dibble
www.stic-cil.org
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