package Student;  #tell Perl we're creating a new class called Student

sub new{ #begin constructor
    my $class = shift;  #class name is first argument passed to function
    my $ref = {Name => "", ID => 0}; #initialize class variables
    bless($ref, $class); #associate reference with this class
    return $ref;  #return the new class object
}

#Now we have two class methods to set variables, and two to read variables
sub set_name{
    my $ref = shift; #get the object we're operating on
    my $name = shift; #get the value of the name passed in
    $ref->{'Name'} = $name;  #assign the Name parameter to be what was passed in
}

#this function is virtually identical to the first
sub set_RIN{
    my $ref = shift;
    my $rin = shift;
    $ref->{'RIN'} = $rin;
}

#now we have two functions to read the values stored
sub get_name{
    my $ref = shift;  #get the object we're operating on
    my $name = $ref->{'Name'}; #find the Name parameter of that object
    return $name; #return that parameter
}

#deja vu
sub get_RIN{
    my $ref = shift;
    return $ref->{'RIN'};
}

1;

----------------------------------------------------------------------

#!/usr/local/bin/perl -w

use Student; #first, tell Perl we'll be using the Student class we created

#create two new instances of the class Student (using two different methods)
$s1 = new Student; 
$s2 = Student->new;

#Set the names of each student
$s1->set_name("Paul Lalli");
$s2->set_name("Justin McGuire");

#set the RINs of each student
$s1->set_RIN(123121);
$s2->set_RIN(897907);


#Here we create a hash of students, keyed by name, with RINs as values
%students = ($s1->get_name => $s1->get_RIN, 
	     $s2->get_name => $s2->get_RIN);

#Print out each student's info
foreach $name (keys %students){
    print "Student with name $name has RIN $students{$name}\n";
}

--------------------------------------------------------------------

#!/usr/bin/env perl -w
use Math::Complex;

$z = Math::Complex->make(5, 6);
print "z first equals: $z\n";

#Two different ways of calling instance methods:
$real = $z->Re();
$img = Math::Complex::Im($z);

print "The real part of $z is $real, and the imaginary part is $img\n";


#Using overloaded = and +, and constant i
$y = 4 + 3*i;
print "y = $y\n";
$ry = $y->Re();
$iy = $y->Im();
print "Real y = $ry\tImg y = $iy\n";

#More overloading
$x = 10 + 5*i + $z;
print "x = $x\n";
$rx = $x->Re();
$ix = $x->Im();
print "Real x = $rx\tImg x = $ix\n";

#Setting pieces of complex numbers, the way the writer intended
$x->Re(20);
$x->Im(40);
print "x is now = $x\n";


#Demonstrating that class variables are not private
${$z->cartesian}[0] = 40;  #Don't do this!!!
$real = $z->Re();
$img = Math::Complex::Im($z);

print "The real part of $z is $real, and the imaginary part is $img\n";