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8 CHANGED: TBrowse error handling
------------------------------------------------------------------------------
Assigning invalid data to TBrowse and TBColumn
instance variables would not generate an error in
Clipper 5.01. Type checking during instance
variable assignment has been added in Clipper 5.01a
to trap invalid values and produce a recoverable
runtime error.
The problem commonly occurs when assigning a NIL
value to an instance variable as a result of an
optional parameter:
FUNCTION MyBrowse( nTop, nLeft, nBottom, nRight, cHeadSep )
oBrowse := TBrowseNew( nTop, nLeft, nBottom, nRight )
// If only four arguments are passed to this
// function the following line will assign a NIL
// to headSep, resulting in an error.
oBrowse:headSep := cHeadSep
The following example prevents accidentally
assigning a NIL to a TBrowse instance variable when
a function accepts optional parameters.
FUNCTION MyBrowse( nTop, nLeft, nBottom, nRight, cHeadSep )
oBrowse := TBrowseNew( nTop, nLeft, nBottom, nRight )
// don't assign a NIL - headSep has a default value.
IF cHeadSep != NIL
oBrowse:headSep := cHeadSep
ENDIF
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