http://qs321.pair.com?node_id=152897


in reply to Beginner's Object Orientation Exercises?

Ok, here's TRY 2. I'm almost 100% percent sure this is real object orientation. It's a package called AlienFarm that can make, teach, and give powers to aliens. (Constructed using the birth method.)

#! Perl
use strict;


{
package AlienFarm;

sub birth {
    my $self=shift;
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime
+(time);
    my $name=shift;
    $mon+=1;
    $year+=1900;
    my $birth = "$mon $mday, $year";
    my $alien = bless {
        NAME => "$name",
        BIRTH => "$birth",
        POWERS => [ ],
        BRAINS => ["pre-school", "1st grade", "2nd grade",
                     "3rd grade", "4th grade", "5th grade",
                     "6th grade", "7th grade", "8th grade",
                     "9th grade", "10th grade", "11th grade",
                     "12th grade", "Harvard Freshman", "Harvard Sophmo
+re",
                     "Havard Junior", "Harvard Senior", "Employed", "C
+EO"],
        LEVEL => "-1" }, "AlienFarm";
}
sub birthday {
    my $decide=shift;
    ref $decide ? $decide->{BIRTH} : "an unknown time";
}
sub name {
    my $decide=shift;
    ref $decide ? $decide->{NAME} : "an unknown name";
}
sub set_power {
    my $self=shift;
    my $power=shift;
    push @{$self->{POWERS}}, $power;
}
sub get_powers {
    my $self=shift;
    my $num=1;
    foreach my $power ( @{$self->{POWERS}} ) {
    print "$num) $power\n";
    $num++;
    }
    print "\n";
}
sub teach_lessons {
    my $self=shift;
    my $level = $self->{LEVEL};
    $level+=1;
    $self->{LEVEL} = $level;
    return "Lesson taught. Level: ". $self->{BRAINS}[$self->{LEVEL}] .
+"\n";

}
sub schooling {
    my $self = shift;
    return $self->{BRAINS}[$self->{LEVEL}];
}
}

[download]

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

Replies are listed 'Best First'.
Re: Re: Beginner's Object Orientation Exercises?
by Necos (Friar) on Mar 21, 2002 at 00:45 UTC
    Here's a slightly modified version of your AlienFarm module... There are some subtle differences... Can you see what they are?
    #!/usr/bin/perl -w
package AlienFarm;
use strict;

sub birth {
    my $pkg = shift;
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)=localtime
+(time);
    my $name = shift;
    $mon++;
    $year+=1900;
    my $birth = "$mon $mday, $year";
    my $alien = bless {
        NAME => "$name",
        BIRTH => "$birth",
        POWERS => [ ],
        BRAINS => ["pre-school", "1st grade", "2nd grade",
                     "3rd grade", "4th grade", "5th grade",
                     "6th grade", "7th grade", "8th grade",
                     "9th grade", "10th grade", "11th grade",
                     "12th grade", "Harvard Freshman", "Harvard Sophmo
+re",
                     "Havard Junior", "Harvard Senior", "Employed", "C
+EO"],
        LEVEL => "-1" }, $pkg;
}
sub birthday {
    my $decide=shift;
    ref $decide ? $decide->{BIRTH} : "an unknown time";
}
sub name {
    my $decide=shift;
    ref $decide ? $decide->{NAME} : "an unknown name";
}
sub set_power {
    my $self=shift;
    my $power=shift;
    push @{$self->{POWERS}}, $power;
}
sub get_powers {
    my $self=shift;
    my $num=1;
    foreach my $power ( @{$self->{POWERS}} ) {
    print "$num => $power\n";
    $num++;
    }
    print "\n";
}
sub teach_lessons {
    my $self = shift;
    $self->{LEVEL}++;
    return "Lesson taught. Level: ". $self->{BRAINS}[$self->{LEVEL}] .
+"\n";

}
sub schooling {
    my $self = shift;
    return $self->{BRAINS}[$self->{LEVEL}];
}

    [download]

    Also, you can actually combine set_power and get_power into one sub, called power. But that's an exercise left for the reader...

    Theodore Charles III
    Network Administrator
    Los Angeles Senior High
    4650 W. Olympic Blvd.
    Los Angeles, CA 90019
    323-937-3210 ext. 224
    email->secon_kun@hotmail.com
[reply]
[d/l]
      I think that I could change 
      sub set_power {
    my $self=shift;
    my $power=shift;
    push @{$self->{POWERS}}, $power;
}
sub get_powers {
    my $self=shift;
    my $num=1;
    foreach my $power ( @{$self->{POWERS}} ) {
    print "$num => $power\n";
    $num++;
    }
    print "\n";
}

      [download]
      into something like: 
      sub power {
    my $self=shift;
    if ($_[0]) {  
        my $power=shift;
        push @{$self->{POWERS}}, $power;
    } else {
        my $self=shift;
        my $num=1;
        foreach my $power ( @{$self->{POWERS}} ) {
        print "$num => $power\n";
        $num++;
        }
        print "\n";
    }
}

      [download]
      It would be called as $obj->power("Power name") to set, and $obj->power() to view.

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

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