Assigning a cell value to a variable - between different workbooks

How, without opening the source workbook, copy the contents of a cell and put it in a variable in the destination workbook?

Example:

valueX = "='c:\code\[example.xlsx]Sheet1'!R2C1"
MsgBox (valueX)

The result is ='c:\code\[example.xlsx]Sheet1'!R2C1
and not the value XPTO

If I assign the reference to a cell directly, it work:

Range("A1").Value="='c:\code\[example.xlsx]Sheet1'!R2C1"
MsgBox(Range("A1").Value)

The result is XPTO