my $val = $obj->reader;
$obj->write( $newval); 
##</code><code>##

#!/usr/bin/perl --

package QuackLog;
use Moose;
use namespace::autoclean;
use strict;

my @log_string_parts =
  qw(timestamp foo bar baz qux norf quack honk woof meow blerf);

has $_=> ( is => 'rw' ) for @log_string_parts;

has qw/ log_string is rw  isa Str  lazy 1 builder _get_log_string /;

sub _get_log_string {
    my ($self) = shift;
    my $str = join ' ', map {;
        my $str = $self->$_;
        length $str ? $str : ''
    } @log_string_parts;
    return $self->log_string( $str );
}

sub set_log_string {
    my ( $self, $s ) = @_;
    my @part_values = split / /, $s;
    for my $method (@log_string_parts) {
        $self->can($method);
        $self->$method( shift @part_values );
    }
    return $self->_get_log_string;
}
__PACKAGE__->meta->make_immutable();

package main;
use strict;
use warnings;

my $ql = QuackLog->new ;
dd( empty => $ql );
$ql->qux('qux');
dd( single => $ql );
dd( single => $ql->log_string );
dd( double => $ql );
dd( full => $ql->set_log_string( q/timestamp foo bar baz qux norf quack honk woof meow blerf/ ) );
dd( full => $ql->log_string );
$ql->qux('XXXXXX'); ## uh oh, log_string not updated
dd( full => $ql , $ql->log_string );
__END__

("empty", bless({}, "QuackLog"))
("single", bless({ qux => "qux" }, "QuackLog"))
("single", "    qux      ")
(
  "double",
  bless({ log_string => "    qux      ", qux => "qux" }, "QuackLog"),
)
(
  "full",
  "timestamp foo bar baz qux norf quack honk woof meow blerf",
)
(
  "full",
  "timestamp foo bar baz qux norf quack honk woof meow blerf",
)
(
  "full",
  bless({
    bar        => "bar",
    baz        => "baz",
    blerf      => "blerf",
    foo        => "foo",
    honk       => "honk",
    log_string => "timestamp foo bar baz qux norf quack honk woof meow blerf",
    meow       => "meow",
    norf       => "norf",
    quack      => "quack",
    qux        => "XXXXXX",
    timestamp  => "timestamp",
    woof       => "woof",
  }, "QuackLog"),
  "timestamp foo bar baz qux norf quack honk woof meow blerf",
)
##</code><code>##

#!/usr/bin/perl --

package QuackLog;
use Moose;
use namespace::autoclean;
use strict;

my @log_string_parts =
  qw(timestamp foo bar baz qux norf quack honk woof meow blerf);

my $clearer = sub { $_[0]->clear_log_string };
has $_=> ( is => 'rw' , trigger => $clearer ) for @log_string_parts;

has qw/ log_string is rw  isa Str  lazy 1 builder _get_log_string clearer clear_log_string /;

sub _get_log_string {
    my ($self) = shift;
    my $str = join ' ', map {;
        my $str = $self->$_;
        length $str ? $str : ''
    } @log_string_parts;
    return $self->log_string( $str );
}

sub set_log_string {
    my ( $self, $s ) = @_;
    my @part_values = split / /, $s;
    for my $method (@log_string_parts) {
        $self->can($method);
        $self->$method( shift @part_values );
    }
    return $self->_get_log_string;
}
__PACKAGE__->meta->make_immutable();

package main;
use strict;
use warnings;

my $ql = QuackLog->new ;
dd( empty => $ql );
$ql->qux('qux');
dd( single => $ql );
dd( single => $ql->log_string );
dd( double => $ql );
dd( full => $ql->set_log_string( q/timestamp foo bar baz qux norf quack honk woof meow blerf/ ) );
dd( full => $ql->log_string );
$ql->qux('XXXXXX'); ## uh oh, log_string not updated
dd( full => $ql , $ql->log_string );

__END__


("empty", bless({}, "QuackLog"))
("single", bless({ qux => "qux" }, "QuackLog"))
("single", "    qux      ")
(
  "double",
  bless({ log_string => "    qux      ", qux => "qux" }, "QuackLog"),
)
(
  "full",
  "timestamp foo bar baz qux norf quack honk woof meow blerf",
)
(
  "full",
  "timestamp foo bar baz qux norf quack honk woof meow blerf",
)
(
  "full",
  bless({
    bar        => "bar",
    baz        => "baz",
    blerf      => "blerf",
    foo        => "foo",
    honk       => "honk",
    log_string => "timestamp foo bar baz XXXXXX norf quack honk woof meow blerf",
    meow       => "meow",
    norf       => "norf",
    quack      => "quack",
    qux        => "XXXXXX",
    timestamp  => "timestamp",
    woof       => "woof",
  }, "QuackLog"),
  "timestamp foo bar baz XXXXXX norf quack honk woof meow blerf",
)