package MyDEBUGLOG;
    use Tie::Handle;
    @ISA = qw/Tie::Handle/;

    sub TIEHANDLE {
        my $class = shift;
        bless {}, $class;
    }

    {
        my $line = 0;
        sub PRINT {
            my $self = shift;
            ++$line;
            print DEBUGLOG map "$line: $_", @_;
        }
    }

    package main;
    tie *DEBUGLOG, 'MyDEBUGLOG';

    print DEBUGLOG "Foo";