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copied!<p>@Mark Biek Your keyExists closely matches my standard Exists() function. To make the class more useful for COM-exposed collections and checking for numeric indexes, I'd recommend changing sKey and myCollection to not be typed. If the function is going to be used with a collection of objects, 'set' is required (on the line where val is set).</p> <p><strong>EDIT</strong>: It was bugging me that I've never noticed different requirements for an object-based and value-based Exists() function. I very rarely use collections for non-objects, but this seemed such a perfect bottleneck for a bug that would be so hard to track down when I needed to check for existence. Because error handling will fail if an error handler is already active, two functions are required to get a new error scope. Only the Exists() function need ever be called:</p> <pre><code>Public Function Exists(col, index) As Boolean On Error GoTo ExistsTryNonObject Dim o As Object Set o = col(index) Exists = True Exit Function ExistsTryNonObject: Exists = ExistsNonObject(col, index) End Function Private Function ExistsNonObject(col, index) As Boolean On Error GoTo ExistsNonObjectErrorHandler Dim v As Variant v = col(index) ExistsNonObject = True Exit Function ExistsNonObjectErrorHandler: ExistsNonObject = False End Function </code></pre> <p>And to verify the functionality:</p> <pre><code>Public Sub TestExists() Dim c As New Collection Dim b As New Class1 c.Add "a string", "a" c.Add b, "b" Debug.Print "a", Exists(c, "a") ' True ' Debug.Print "b", Exists(c, "b") ' True ' Debug.Print "c", Exists(c, "c") ' False ' Debug.Print 1, Exists(c, 1) ' True ' Debug.Print 2, Exists(c, 2) ' True ' Debug.Print 3, Exists(c, 3) ' False ' End Sub </code></pre>

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