(perl subs use call-by-value, which makes a copy)
I don't think this is true.
report_mem( 'program start' );
my $big = 'x' x 100_000_000;
report_mem( 'after making big string' );
take_big_arg( $big );
sub take_big_arg {
printf "got %d characters\n", length $_[0];
report_mem( 'passed to function' );
}
sub report_mem {
my ( $msg ) = @_;
printf "%d %s\n", my_mem(), $msg;
}
sub my_mem {
my ($proc_info)
= grep { $_->[2] == $$ } map { [ split ] } `ps l | tail -n +2`
+;
return $proc_info->[6];
}
__END__
13124 program start
208444 after making big string
got 100000000 characters
208444 passed to function
The truth is Perl gives the sub aliases to the variables you pass. Common practice is to copy them after that (my ($copy) = @_), but that's something else.