package Flashlight;

sub new {
   my $class = shift;
   my $power = shift || 0;
   my $level = shift || 0;

   my $self  = {
      level => $level,
      power => $power,
   };

   return bless $self, $class;
}
[download]

my $light = Flashlight->new(1,4);
[download]

Next, you really shouldn't print messages to STDOUT inside an object's method(s). Instead, methods really should generally only get and set values. This means that your methods Flash and ChangePowerLevel really belong in the client that uses your Flashlight object. Also, pwrlvl and ison should return true or false values, and should be renamed to more standard names like change_level and is_on.

Here is a complete re-write of your good but flawed first attempt (don't fret it, OO is an art form that takes a looong time to 'get'). Like music, this is just my interpretation of the problem at hand.

I made a Flashlight program.

A program? I thought you wanted to exercise OO? Object properties are usually stored in the object itself, so that you can create multiple instances. If in your program you find that you need another flash light, you'll have to duplicate your entire package, or at least modify it heavily, to support multiple on/off states.

I took the liberty of re-writing it, so you can OO the other machines yourself.

package Flashlight;
use Carp;
use Time::HiRes qw/usleep/;
use strict;

sub new {
    my ($class, %options) = @_;
    my $self = { };
    my @required = qw/color/;
    my @optional = qw/batteries_included type battery_type/;
    for (@required) {
        croak "Required named argument $_ was not defined"
            if not defined $options{$_};
        $self->{$_} = $options{$_};
    }
    for (@optional) {
        $self->{$_} = $options{$_} if exists $options{$_};
    }
    return bless $self, $class;
}

sub color {
    my ($self) = @_;
    return lc $self->{color};
}

sub charge_batteries {
    my ($self, $type) = @_;
    carp 'Please read the manual!'
        if defined $type and $type ne $self->{battery_type};
    return $self->{batteries_included} = 1;
}

sub is_on {
    my ($self) = @_;
    return $self->{on};
}

sub is_off {
    my ($self) = @_;
    return ! $self->{off};
}

sub on {
    my ($self) = @_;
    return undef if not $self->{batteries_included};
    $self->{on} = 1;
    return return 1;
}

sub off {
    my ($self) = @_;
    return $self->{on} = 0;
}

sub switch {
    my ($self) = @_;
    return undef if $self->is_off and not $self->{batteries_included};
    return $self->{on} = ! $self->{on}
}

sub flash {
    my ($self, $duration) = @_;
    croak 'Cannot flash while on' if $self->is_on;
    croak 'Cannot flash for a negative number of seconds' if $duration
+ < 0;
    carp 'flash() should be used to do nothing at all, changing durati
+on'
        if defined $duration and $duration == 0;
    $duration ||= 0.1;
    $self->on();
    usleep $duration;
    $self->off();
}
[download]

Now, it's your turn. I can say only one thing: try harder.

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk

I think I'm understanding better now. I read boot over again, and I payed more attention this time. I'm working on an exercise now, which will hopefully be better than the last.

> munchie, the number munchin newb
Llama: The other other white meat!
(you had to be there :-P)