tasks a-s

Task/Polymorphic-copy/Perl/polymorphic-copy.pl

@@ -0,0 +1,53 @@
+package T;
+sub new {
+        my $cls = shift;
+        bless [ @_ ], $cls
+}
+
+sub set_data {
+        my $self = shift;
+        @$self = @_;
+}
+
+sub copy {
+        my $self = shift;
+        bless [ @$self ], ref $self;
+}
+
+sub manifest {
+        my $self = shift;
+        print "type T, content: @$self\n\n";
+}
+
+package S;
+our @ISA = 'T';
+# S is inheriting from T.
+# 'manifest' method is overriden, while 'new', 'copy' and
+# 'set_data' are all inherited.
+sub manifest {
+        my $self = shift;
+        print "type S, content: @$self\n\n";
+}
+
+package main;
+
+print "# creating \$t as a T\n";
+my $t = T->new('abc');
+$t->manifest;
+
+print "# creating \$s as an S\n";
+my $s = S->new('SPQR');
+$s->manifest;
+
+print "# make var \$x as a copy of \$t\n";
+my $x = $t->copy;
+$x->manifest;
+
+print "# now as a copy of \$s\n";
+$x = $s->copy;
+$x->manifest;
+
+print "# show that this copy is indeed a separate entity\n";
+$x->set_data('totally different');
+print "\$x is: ";
+$x->manifest;