vba-variant: how to handle Class vs. primitive types

问题

my function gets a collection and the items may be Objects or primitives how can I assign the item to a variant?

What I do now looks something like this:

Dim vItem As Variant
On Error Resume Next
vItem = oCollection.Item(sKey)
If Err.Number = 91 Then
    Set vItem = oCollection.Item(sKey)
On Error GoTo 0

I think it works, but I wonder if there is a better way to do it.

回答1:

You may use the varType() function to test the type, alternatively if you are testing for specific types, you could use typeof.

        If VarType(oCollection.Item(sKey)) = vbObject Then
           Set vItem = oCollection.Item(sKey)
        Else
            vItem = oCollection.Item(sKey)
        End If

回答2:

A slight improvement to the answer from @SWa is to create a helper function; this avoids having to copy/paste, for example, the oCollection.Item(sKey) part of op's answer.

Sub SetThisToThat(ByRef this As Variant, ByRef that As Variant)
    If IsObject(that) Then
        Set this = that
    Else
        this = that
    End If
End Sub

Some tests as an example:

Function Test()
    Call SetThisToThat(Test, "Function test")
End Function

Sub RunTest()
    MsgBox Test

    Dim s As String
    Call SetThisToThat(s, "Why must it be this hard?")
    MsgBox s
End Sub

@TmTron should use:

Call SetThisToThat(vItem, oCollection.Item(sKey))

来源：https://stackoverflow.com/questions/21572437/vba-variant-how-to-handle-class-vs-primitive-types