MI: "freezing" variable object

[Vladimir Prus]

Hi,
what's the best way to "freeze" a variable object, so that it's current
value is saved, and is not changed on any -var-update invocation? 

I need this in order to implement a functionality where user can remember
the current value of an expression for future reference. I'd expect the
user to still be able to open composite object (using -var-list-children),
so saving just textual representation I not enough.

I can get the desired effect with:

   print expression
   -var-create $NNN

where $NNN is the history item, but am I supposed to use CLI command for
that?

- Volodya