Solution to 27.2 in Perl 5

1 files changed, 66 insertions, 0 deletions

diff --git a/challenge-027/joelle-maslak/perl5/ch-2.pl b/challenge-027/joelle-maslak/perl5/ch-2.pl
new file mode 100755
index 0000000000..e45a5cdd15
--- /dev/null
+++ b/challenge-027/joelle-maslak/perl5/ch-2.pl
@@ -0,0 +1,66 @@
+#!/usr/bin/env perl
+use v5.22;
+use strict;
+use warnings;
+
+# Turn on method signatures
+use feature 'signatures';
+no warnings 'experimental::signatures';
+
+# Limitation - this only tracks the scalar container, not changes to
+# nested objects.
+
+package History {
+    use Moose;
+    use feature 'signatures';
+    no warnings 'experimental::signatures';
+
+    has hist => (
+        is      => 'rw',
+        isa     => 'ArrayRef',
+        default => sub { [] },
+    );
+    has data => ( is => 'rw', );
+
+    sub FETCH($self) {
+        return $self->data;
+    }
+
+    sub STORE ( $self, $value ) {
+        $self->data($value);
+        push $self->hist->@*, $value;
+
+        return $value;
+    }
+
+    sub TIESCALAR($self) {
+        return $self->new();
+    }
+
+    sub history($self) {
+        return $self->hist->@*;
+    }
+}
+
+MAIN: {
+    my $x;
+    my $hist = tie $x, 'History';
+
+    $x = 10;
+    $x = 20;
+    $x -= 5;
+
+    $x = 'Foo!';
+
+    # A new instance of history should be independnet.
+    my $z;
+    my $hist2 = tie $z, 'History';
+    $z = 3;    # Won't show up in history for $x.
+
+    # And we just set the original history, the one we log, to a new
+    # value
+    $x = 'Baz.';
+
+    say join( "\n", $hist->history );
+}
+