Set a cell value from a function

Question

The contents of cell A1 is =test(2) where test is the function:

Function test(ByRef x As Double) As Double
  Range(\"A         


        

Answer 1

When you call a function from a worksheet cell, you are effectively using the function as a User Defined Function, which has the limitations as described here:

http://support.microsoft.com/kb/170787

In the text there is a line:

Any environmental changes should be made through the use of a Visual Basic subroutine.

It's interesting how they use the word should rather than must. I wonder if the author of the KB knew that environment changes can happen from a VBA Function.

Now, when you call the function from another VBA Sub / Function, it is treated differently. From the help docs (sorry I couldn't find a web page reference - basically, in VBE, highlight the word Function and press F1):

Like a Sub procedure, a Function procedure is a separate procedure that can take arguments, perform a series of statements, and change the values of its arguments. However, unlike a Sub procedure, you can use a Function procedure on the right side of an expression in the same way you use any intrinsic function, such as Sqr, Cos, or Chr, when you want to use the value returned by the function.

So it sounds like Subs and functions can do the same things when used in VBA only, except that Functions can return values back to the calling function/sub.

This is pretty interesting, actually, since Excel can call a function with some sort of "Read-Only" restriction to Excel's environment.

I think that, in the end, Excel can call the function from a worksheet cell in a different way than VBA does. When you call it from a Cell, it's considered a User Defined Function, which includes the restrictions of changing Excel's environment. Where when called from within VBA (where the original caller from a chain of calls is from VBA), it has all the power a Sub does, plus it can return values.

Answer 2

Due to Function fundamentals which state that you can not change or set sheet cells. You need to delete the row with Range("A2") = x

EDIT Some additional link (which I believe is always useful to provide for those who want to analyse UDF topic): Creating custom functions by Microsoft

Answer 3

I've adapted your code to work for strings and functions and anything else in-between I hope (still testing).

Alot of questions resulting from testing, but 2 come to mind first:

What other ways could you use to execute / process the parameters and return the desired results;

a. As I have done b. Not as I have done (i.e. differently).

Many thanks to Rick Rothstein MrExcel MVP & many others on SO for enabling & helping for this to happen.

Function MOVEME27(a As Variant, b As Variant, Optional CELLR As Variant, Optional cellq As Variant) '21/05/2018 works copied to ar4' 03/06/2019 23:30 was cellr as range , cellq as range - changed to variants
 Dim WTVR1 As Variant '' ''20/05/2019'' '09/06/2019 Code by S Tzortzis/David Wooley
 Dim WTVR2 As Variant
 Dim P As String
 Dim P1 As String
 Dim bb As String
 Dim bb1 As String
 Dim A1 As Long
 Dim A2 As Long

 Dim c As String

 'x' a = Evaluate(a)
P = Chr(34) & a & Chr(34)
P2 = Chr(34) & [P] & Chr(34)

bb = Chr(34) & b & Chr(34)
bb1 = Chr(34) & [bb] & Chr(34)

c = Chr(34) & CELLR & Chr(34)
f = Chr(34) & callq & Chr(34)


'P2 = Chr(34) & "'''" & [P] & "'''" & Chr(34)
'p1 = Chr(34) & p & Chr(34)

''WTVR1 = "MOVEUS1(" & Application.Caller.Offset(0, 2).Address(False, False) & "," & Chr(34) & P2 & Chr(34) & "," & b & ")"
   WTVR1 = "MOVEUS11h(" & Application.Caller.Offset(0, 2).Address(False, False) & "," & [P2] & "," & [bb1] & ")"
Evaluate WTVR1


WTVR2 = "MOVEUS22h(" & Application.Caller.Offset(0, 1).Address(False, False) & "," & [P2] & "," & [bb1] & ")" ' used or be adjacent - maybe redo rhat pr put a GO TO sub. '' ''20/05/2019''

Evaluate WTVR2

A1 = cellq.Row
A2 = cellq.Column

CELLRR = Chr(34) & CELLR & Chr(34)
CELLRR1 = Chr(34) & [CELLRR] & Chr(34)
cellqq = Chr(34) & cellq & Chr(34)
cellqq1 = Chr(34) & [cellqq] & Chr(34)


''wtvr3 = "CopyFrom.Parent.Evaluate CopyOver234h(" & c & "," & f & ")" ''''20190531 1929
wtvr31 = "MOVEUS33h(" & Application.Caller.Offset(A1 - ActiveCell.Row + 1, A2 - ActiveCell.Column).Address(False, False) & "," & [CELLRR] & "," & [cellqq] & ")"

    Evaluate wtvr31

MOVEME27 = "Hello world       " & " / " & WTVR1 & " / " & WTVR2 & "\\\\\/////" & wtvr31 & "\\\\\/////---" & ActiveCell.Row - A1 & "//////---" & ActiveCell.Column - A2

' DO AS WHATVER = "MOVEUS3(" APPLICATION.CALLER.OFFSET(THE ROW & COLUMN IE CELL         YOU REFERENCES IN a as variant (copy from)'
    'with ="" in sub 30052019 19:28

    'CopyFrom.Parent.Evaluate "CopyOver2(" & CELLR.Address(False, 1) & "," &              CELLR.Address(False, False) & ")"  ''''2019050 1929



    End Function

    Private Sub MOVEUS11h(CELL1 As Range, G1 As Variant, G2 As Variant)

        '[ak333] = a


        CELL1 = Chr(34) & G1 & Chr(34) & "B" & "//" & G2


    End Sub


    Private Sub MOVEUS22h(CELL2 As Range, G3 As Variant, G4 As Variant)

        CELL2 = Chr(34) & G3 & Chr(34) & "<>" & G4

    End Sub

    '' with chr(34) arond the p's and a's in sub or fucntion changes behavior. thinking of doing if a is string, then a=x , x as string, if not kep as variant
    ''27/05/2019 :(

    '''''30/05/2019 .....'''''''


    '------------------------------------------------------------------------------- ADD THIS 30052019 -------------------------------
    'private sub Movus3(cellfrom as range, cellto as range)
    'End Sub

    Private Sub moveus33h(cell3 As Range, CopyFrom As Variant, copyTo As Variant) ''''2019050 1929 ''' 03062019 change ema back to as Range here. :)
       '' copyTo.Value = CopyFrom.Value ''''2019050 1929

       ''CopyFrom.Value = ""

       cell3 =  CopyFrom  'Chr(34) & CopyFrom & Chr(34)

    End Sub ''''2019050 1929

Answer 4

Yes, you can have your own user defined function which writes values to any cell, not just the one which you type in the formula.

Here is a simple example. The UDF function takes two arguments A and B and returns their product A*B. But what is interesting it returns the result in the adjacent cell just to the right of the cell in which we entered the formula.

Put this code in standard VBA module:

Function UDF_RectangleArea(A As Integer, B As Integer)
    Dim MagicSpell As String
    MagicSpell = "Adjacent(" & Application.Caller.Offset(0, 1).Address(False, False) & "," & A & "," & B & ")"
    Evaluate MagicSpell
    UDF_RectangleArea = "Hello world"
End Function

Private Sub Adjacent(CellToChange As Range, A As Integer, B As Integer)
    CellToChange = A * B
End Sub

Now type in B2 the formula: =UDF_RectangleArea(3,4)

The function returns results in two cells: "Hello world" in B2 (which is not surprising) and the rectangle area in C2 (which is a rabbit out of a hat). Both results as well as the place of "rabbit" appearance can be easily customized. The job is done by the VBA EVALUALTE command. The value of variable MagicSpell becomes in this case Adjacent(C2,3,4) which is fired from within the UDF before the UDF result is returned. Have fun!