Pass array to ParamArray

Question

is it possible to pass all elements of an array to a ParamArray?

For example I'd like to pass a ParamArray to another ParamArray:

Sub test()
    p1 "test", "banane", "birne"
End Sub

Sub p1(ParamArray keys() As Variant)
    p2 keys 'should be the same as: p2 "test", "banane", "birne"
End Sub

Sub p2(ParamArray keys() As Variant)
    Dim key As Variant
    For Each key In keys
        Debug.Print key 'Run-time error '13' Type mismatch (key is an array)
    Next key
End Sub

In this case ParamArray of p2 doesn't contain the elements of keys, but it gets the array-object keys. Thus I've got to check, if an arrays is passed:

Sub test()
    p1 "test", "banane", "birne"
    p2 "test", "banane", "birne"
End Sub

Sub p1(ParamArray keys() As Variant)
    p2 keys
End Sub

Sub p2(ParamArray params() As Variant)
    Dim keys As Variant
    If IsArray(params(0)) Then
        keys = params(0)
    Else
        keys = params
    End If

    Dim key As Variant
    For Each key In keys
        Debug.Print key
    Next key
End Sub

But this is awkward for example compared to Java:

public class VarArgs {

    public static void main(String[] args) {
        p1("test", "banane", "birne");
        p2("test", "banane", "birne");

        String[] array = {"test", "banane", "birne"};
        p1(array);
        p2(array);
    }

    public static void p1(String... strings) {
        p2(strings);
    }

    public static void p2(String... strings) {
        for (String string : strings) {
            System.out.println(string);
        }
    }

}

In Java I don't have to distinguish. But this is probably not possible in VBA.

Thanks for help,
Michael

Answer 1

Pass a ParamArray argument to another function that expects a ParamArray argument (delegate ParamArray arguments). I need to delegate to a function of type: strf(str as string, ParamArray args() as Variant) as String the arguments received in other function in a ParamArray passing directly without explicitly write. The restrictions I've found are:

1. A ParamArray() it can only be passed to another function that expects a ParamArray.
2. The ParamArray is received at element 0 as a Variant ()
3. When the second function receives it increases a level of depth I have not found any satisfactory solution, but I have written a function that works perfectly, undoing the depth levels added and returning a vector with arguments received.

Code:

Option Explicit
Option Base 1

Public Sub PrAr1(ParamArray pa1() As Variant)
Dim arr() As Variant
  arr = fn.ParamArrayDelegated(pa1)
  PrAr2 pa1
End Sub

Public Sub PrAr2(ParamArray pa2() As Variant)
Dim i As Integer, arrPrms() As Variant
  arrPrms = fn.ParamArrayDelegated(pa2)
  For i = 0 To UBound(arrPrms)
    Debug.Print s.strf("i: %0 prm: %1 ", i, arrPrms(i))
  Next i
  PrAr3 pa2
End Sub

Public Sub PrAr3(ParamArray pa3() As Variant)
Dim i As Integer, arrPrms() As Variant
  arrPrms = fn.ParamArrayDelegated(pa3)
  For i = 0 To UBound(arrPrms)
    Debug.Print s.strf("i: %0 prm: %1 ", i, arrPrms(i))
  Next i
End Sub

Public Function ParamArrayDelegated(ParamArray prms() As Variant) As Variant
Dim arrPrms() As Variant, arrWrk() As Variant
'When prms(0) is Array, supposed is delegated from another function
  arrPrms = prms
  Do While VarType(arrPrms(0)) >= vbArray And UBound(arrPrms) < 1
    arrWrk = arrPrms(0)
    arrPrms = arrWrk
  Loop
  ParamArrayDelegated = arrPrms
End Function

Answer 2

you could convert it into a Variant from the 2nd call on:

Sub test()
    p1 "test", "banane", "birne"
End Sub

Sub p1(ParamArray keys() As Variant)
    p2 CVar(keys) '<--| pass it as a Variant
End Sub

Sub p2(keys As Variant) '<--| accept a Variant argument
    Dim key As Variant

    For Each key In keys
        Debug.Print key
    Next key
End Sub

Answer 3

Here's my solution. Note that Its one restriction is that you can pass only one (Variant) array argument to the ParamArray parameter set. Possibly it could be generalized to handle multiple passed arrays but I have yet to run into that need.

Option Explicit

Sub test()
    p1 "test", "banane", "birne"
    p2 "test", "banane", "birne"
End Sub


Sub p1(ParamArray keys() As Variant)
    Dim TempKeys As Variant

    TempKeys = keys 'ParamArray isn't actually a standard Variant array, so you have to copy
                    'it to one in order for the added test/workaround in p2 to not crash
                    'Excel.

    p2 TempKeys 'should be the same as: p2 "test", "banane", "birne"
End Sub

Sub p2(ParamArray keys() As Variant)
    Dim key As Variant

    If IsArray(keys(0)) Then keys = keys(0) 'Set this routine's ParamArray parameter to be
                                            'the array of its first element.

    For Each key In keys
        Debug.Print key
    Next key
End Sub

Answer 4

Try:

Sub p2(ParamArray keys() As Variant) 
dim myKey as Variant  
 If IsArray(keys(0)) Then
        myKey = keys(0)
    Else
        myKey = keys()
 End If

...
end sub

Answer 5

Sub test()
    p1 "test", "banane", "birne"
End Sub

Sub p1(ParamArray keys() As Variant)
    p2 keys
End Sub

Sub p2(ParamArray keys() As Variant)
    Dim key As Variant
    For Each key In keys
        Debug.Print key(0) '<- Give an Index here.
    Next key
End Sub

Answer 6

paramArrays are weird but you can use normal Array, which works just fine

 Sub test()
    Dim a As Variant: a = Array("test", "banane", "birne")
    p1 a
End Sub

Sub p1(keys As Variant)
    p2 keys
End Sub

Sub p2(keys As Variant)
    Dim key As Variant
    For Each key In keys
        Debug.Print key
    Next key
End Sub