In trying to solve a problem with some code I inherited I stumbled upon the DataType function of LotusScript, which I'd never used before.

My code was calling a function and expecting a List of Strings back. Like so:

Dim aList as Variant
aList = MakeMeAList()
Msgbox aList("Foo2")

The function which built this list of strings looked something like:

Function MakeMeAList() as Variant
 Dim theList List As String
 theList("Foo1") = "bar1"
 theList("Foo2") = "bar2"
 MakeMeAList = theList
End Function

Obviously the code was a bit more complicated than that. What it actually did was look for a profile for a supplied username and then return details of the user. If a profile couldn't be found it just added an item to the List called "Error".

The trouble with the code was that this error approach didn't seem to work and I just kept on getting "variant doesn't contain a container". The only way I found by which I could safely test whether I'd got a List back was using this new-found DataType function, as below:

Dim aList as Variant
aList = MakeMeAList()
If DataType(aList)=2056 Then 'Variant(2048) + String(8) = 2056
 Messagebox aList("Foo2")
Else
 Messagebox "That ain't no list of strings fool!"
End If

You live and learn. Although whether learning new LotusScript techniques at this point in the game is of any use is likely to be debatable.