I am doing pass-by-reference like this:

sub repl {
    local *line = \$_[0]; our $line;
    $line = "new value";
}

sub doRepl {
    my $foo = "old value";
    my ($replFunc) = @_;
    $replFunc->($foo);
    print $foo; # prints "new value";
}

doRepl(\&repl);

Is there a cleaner way of doing it?

Prototypes don't work because I'm using a function reference (trust be that there's a good reason for using a function reference).

I also don't want to use $_[0] everywhere in repl because it's ugly.