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Checking for objects set to nothing in VB

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This is a VB only question.

If I've got a function that has an Optional parameter (a class), how do I check if it's passed or not? The IsMissing() function doesn't seem to work on classes.

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Use a structure like this:

code:

Private Sub Something(Optional clsParam As clsTest)

If clsParam Is Nothing Then
MsgBox "Missing parameter"
Else
MsgBox "Parameter passed"
End If

End Sub


This assumes that the class you're passing has been initialized.

IsMissing only works for optional variants, which is rarely used now that optional parameters can be any data type. This is probably a carryover from VB4 when optional parameters had to be variants.

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