It's a common need to assign a variable to something when entering a
code block, and then revert it upon exit. qscopedvaluerollback can
be used for this. But as a convenience, this patch adds an
extra constructor so that you can "protect" and set a variable
in one go instead of using two lines.
Change-Id: If4b89d3a5ba32ef2304bda058b1b6050932612ed
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>