>>>>> "G" == Guillaume Marcais <guslist / free.fr> writes:

G> Is there anyway to have the same restriction that $SAFE=4 would give
G> except the right to write to already opened IO?

 Use 2 threads :

   * one which open the file and write in
   * other which run with $SAFE = 4

 communication between the 2 threads is made via a queue

Guy Decoux