##
print $foo;
####
sub prepare_foo_print {
my ($foo, $file) = @_;
open my $fh, '>>', $file or die "bummer: $!\n";
my $oldfh = select $fh;
# currently opened $file now is default filehandle
# (instead of STDOUT)
print_whatever ($foo);
select $oldfh;
}
sub print_whatever {
print shift;
}