can excel vba function open a file? - vba

Question

i'm defining a function to save files as .xls format:
Public Function save_as_xls(full_file_path As String) As String
save_as_xls = ""
Dim src_file As Workbook
Set src_file = Workbooks.Open(full_file_path)
src_file.SaveAs filename:=full_file_path, FileFormat:=xlExcel8
src_file.Close
save_as_xls = "OK"
End Function
then call it in excel cell formula as =save_as_xls("c:\temp\test.xls")
However, it doesn't work, the src_file get Nothing from Workbooks.Open
Is there a limitation on vba functions that cannot open files? I only know that it can't write to other cells.

Answer 1

Excel UDF have certain limitations, so you can't save workbook. You may try a workaround with late bound instance of Excel as shown in the below code.
Put this code to the standard module:
Public objExcel As Application
Public Function SaveAsXls(FilePath As String) As String
If objExcel Is Nothing Then
Set objExcel = CreateObject("Excel.Application")
With objExcel
.Visible = True ' for debug
.DisplayAlerts = False
End With
End If
With objExcel
With .Workbooks.Open(FilePath)
.SaveAs _
Filename:=FilePath, _
FileFormat:=xlExcel8
.Close True
End With
End With
SaveAsXls = "OK"
End Function
Put this code to ThisWorkbook section:
Private Sub Workbook_BeforeClose(Cancel As Boolean)
If TypeName(objExcel) = "Application" Then objExcel.Quit
End Sub
So you can call it in Excel cell formula as =SaveAsXls("c:\temp\test.xls")