Hi,

I built a macro that reads data from a text file and returns a string value
from it. When the user puts "=MyMacro(xxx)" in a cell, the returned value
will be some string from my text file. When the user ask Excel to
recalculate the workbook (F9 I believe), my macro is not executed. It will
be executed only if I put "Application.Volatile" as the first line of that
macro. I want the user to be able to trigger a recalculation of all the
cells that use my macro.

Small problem: reading from a file takes a long time. With
Application.Volatile in my macro, any change to any cell in my workbook will
trigger the execution of my macro for every cell that uses it. If my macro
in used in 1000 cells, I don't want the user to wait for 1000 file accesses
each time he writes something in a cell.

My solution to that problem is that I put a "Refresh" button in Excel's menu
to refresh the cells that use my macro. So when the user wants to recalculate
the cells using my macro, he must press the "Refresh" button, else it won't
be recalculated, even after a F9. How do I implement this solution using the
Application.Volatile?

My comprehension of Application.Volatile is that it must be put as the first
line of a macro to make it auto-recalculable. If I want my macro to contain
Application.volatile only in certain circumstances, how do I do it?

I tried to put "Application.Volatile = bFlag" in my macro, bFlag being set
to true only when the "Refresh" menu button is pressed. Doesn't work. Even
worse: in some occasions, once I put the Application.Volatile to false, it
won't go back to true...

Help!
Thanks,
-C.