Add Tie::RefHash::Nestable (lives in Tie/RefHash.pm),

fix a autovivification bug in Tie::RefHash, add tests for both.

Subject: Re: Tie::RefHash: use hash refs as keys in nested hashes
Message-ID: <Pine.LNX.4.21.0011021516010.8344-100000@texel03.doc.ic.ac.uk>

p4raw-id: //depot/perl@7527

1 files changed, 39 insertions, 3 deletions

diff --git a/lib/Tie/RefHash.pm b/lib/Tie/RefHash.pm
index ffa9eb20a0..d4111d92e5 100644
--- a/lib/Tie/RefHash.pm
+++ b/lib/Tie/RefHash.pm
@@ -9,17 +9,26 @@ Tie::RefHash - use references as hash keys
     require 5.004;
     use Tie::RefHash;
     tie HASHVARIABLE, 'Tie::RefHash', LIST;
+    tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST;
 
     untie HASHVARIABLE;
 
 =head1 DESCRIPTION
 
-This module provides the ability to use references as hash keys if
-you first C<tie> the hash variable to this module.
+This module provides the ability to use references as hash keys if you
+first C<tie> the hash variable to this module.  Normally, only the
+keys of the tied hash itself are preserved as references; to use
+references as keys in hashes-of-hashes, use Tie::RefHash::Nestable,
+included as part of Tie::Hash.
 
 It is implemented using the standard perl TIEHASH interface.  Please
 see the C<tie> entry in perlfunc(1) and perltie(1) for more information.
 
+The Nestable version works by looking for hash references being stored
+and converting them to tied hashes so that they too can have
+references as keys.  This will happen without warning whenever you
+store a reference to one of your own hashes in the tied hash.
+
 =head1 EXAMPLE
 
     use Tie::RefHash;
@@ -36,6 +45,11 @@ see the C<tie> entry in perlfunc(1) and perltie(1) for more information.
        print ref($_), "\n";
     }
 
+    tie %h, 'Tie::RefHash::Nestable';
+    $h{$a}->{$b} = 1;
+    for (keys %h, keys %{$h{$a}}) {
+       print ref($_), "\n";
+    }
 
 =head1 AUTHOR
 
@@ -68,7 +82,17 @@ sub TIEHASH {
 
 sub FETCH {
   my($s, $k) = @_;
-  (ref $k) ? $s->[0]{"$k"}[1] : $s->[1]{$k};
+  if (ref $k) {
+      if (defined $s->[0]{"$k"}) {
+        $s->[0]{"$k"}[1];
+      }
+      else {
+        undef;
+      }
+  }
+  else {
+      $s->[1]{$k};
+  }
 }
 
 sub STORE {
@@ -121,4 +145,16 @@ sub CLEAR {
   %{$s->[1]} = ();
 }
 
+package Tie::RefHash::Nestable;
+use vars '@ISA'; @ISA = qw(Tie::RefHash);
+
+sub STORE {
+  my($s, $k, $v) = @_;
+  if (ref($v) eq 'HASH' and not tied %$v) {
+      my @elems = %$v;
+      tie %$v, ref($s), @elems;
+  }
+  $s->SUPER::STORE($k, $v);
+}
+
 1;