use strict ;
use warnings ; 

package FOO ;

sub Principal::bof {
    our $fic;            # Save us from typing $FOO::fic.
    local $fic = "toto"; # 'local' restores $fic when we exit this sub

    # The above can be combined into:
    #    local our $fic = "toto";

    bof2(); 
} 

sub bof2 {
    our $fic;            # Save us from typgin $FOO::fic.
    print $fic;
} 

1;