[vba] VBA: Conditional - Is Nothing

There is an If condition in a VBA application as seen below:

If Not My_Object Is Nothing Then
My_Object.Compute

When the code is run in debug mode, I found that the If condition returns a true even when My_Object has "No Variables".

Could somebody please explain this? I want My_Object.Compute to be executed only when My_Object exists.

Just becuase your class object has no variables does not mean that it is nothing. Declaring and object and creating an object are two different things. Look and see if you are setting/creating the object.

Take for instance the dictionary object - just because it contains no variables does not mean it has not been created.

Sub test()

Dim dict As Object
Set dict = CreateObject("scripting.dictionary")

If Not dict Is Nothing Then
    MsgBox "Dict is something!"  '<--- This shows
Else
    MsgBox "Dict is nothing!"
End If

End Sub

However if you declare an object but never create it, it's nothing.

Sub test()

Dim temp As Object

If Not temp Is Nothing Then
    MsgBox "Temp is something!"
Else
    MsgBox "Temp is nothing!" '<---- This shows
End If

End Sub

In my sample code, I was setting my object to nothing, and I couldn't get the "not" part of the if statement to work with the object. I tried if My_Object is not nothing and also if not My_Object is nothing. It may be just a syntax thing I can't figure out but I didn't have time to mess around, so I did a little workaround like this:

if My_Object is Nothing Then
    'do nothing
Else
    'Do something
End if