support delete() and exists() on array, tied array, and pseudo-hash

elements or slices

p4raw-id: //depot/perl@4796

2 files changed, 35 insertions, 4 deletions

diff --git a/lib/Tie/Array.pm b/lib/Tie/Array.pm
index 3f34c3b81f..5ef83c4781 100644
--- a/lib/Tie/Array.pm
+++ b/lib/Tie/Array.pm
@@ -1,7 +1,8 @@
 package Tie::Array;
 use vars qw($VERSION); 
 use strict;
-$VERSION = '1.00';
+use Carp;
+$VERSION = '1.01';
 
 # Pod documentation after __END__ below.
 
@@ -74,6 +75,16 @@ sub SPLICE
  return @result;
 } 
 
+sub EXISTS {
+    my $pkg = ref $_[0];
+    croak "$pkg dosn't define an EXISTS method";
+}
+
+sub DELETE {
+    my $pkg = ref $_[0];
+    croak "$pkg dosn't define a DELETE method";
+}
+
 package Tie::StdArray;
 use vars qw(@ISA);
 @ISA = 'Tie::Array';
@@ -88,6 +99,8 @@ sub POP       { pop(@{$_[0]}) }
 sub PUSH      { my $o = shift; push(@$o,@_) }
 sub SHIFT     { shift(@{$_[0]}) } 
 sub UNSHIFT   { my $o = shift; unshift(@$o,@_) } 
+sub EXISTS    { exists $_[0]->[$_[1]] }
+sub DELETE    { delete $_[0]->[$_[1]] }
 
 sub SPLICE
 {
@@ -120,6 +133,8 @@ Tie::Array - base class for tied arrays
         
     sub STORE { ... }        # mandatory if elements writeable
     sub STORESIZE { ... }    # mandatory if elements can be added/deleted
+    sub EXISTS { ... }       # mandatory if exists() expected to work
+    sub DELETE { ... }       # mandatory if delete() expected to work
                                
     # optional methods - for efficiency
     sub CLEAR { ... }  
@@ -150,9 +165,11 @@ Tie::Array - base class for tied arrays
 
 This module provides methods for array-tying classes. See
 L<perltie> for a list of the functions required in order to tie an array
-to a package. The basic B<Tie::Array> package provides stub C<DELETE> 
-and C<EXTEND> methods, and implementations of C<PUSH>, C<POP>, C<SHIFT>, 
-C<UNSHIFT>, C<SPLICE> and C<CLEAR> in terms of basic C<FETCH>, C<STORE>, 
+to a package. The basic B<Tie::Array> package provides stub C<DESTROY>,
+and C<EXTEND> methods that do nothing, stub C<DELETE> and C<EXISTS>
+methods that croak() if the delete() or exists() builtins are ever called
+on the tied array, and implementations of C<PUSH>, C<POP>, C<SHIFT>,
+C<UNSHIFT>, C<SPLICE> and C<CLEAR> in terms of basic C<FETCH>, C<STORE>,
 C<FETCHSIZE>, C<STORESIZE>.
 
 The B<Tie::StdArray> package provides efficient methods required for tied arrays 
@@ -203,6 +220,18 @@ deleted.
 Informative call that array is likely to grow to have I<count> entries.
 Can be used to optimize allocation. This method need do nothing.
 
+=item EXISTS this, key
+
+Verify that the element at index I<key> exists in the tied array I<this>.
+
+The B<Tie::Array> implementation is a stub that simply croaks.
+
+=item DELETE this, key
+
+Delete the element at index I<key> from the tied array I<this>.
+
+The B<Tie::Array> implementation is a stub that simply croaks.
+
 =item CLEAR this
 
 Clear (remove, delete, ...) all values from the tied array associated with
diff --git a/lib/Tie/Hash.pm b/lib/Tie/Hash.pm
index 2902efb4d0..928b798e45 100644
--- a/lib/Tie/Hash.pm
+++ b/lib/Tie/Hash.pm
@@ -73,6 +73,8 @@ Return the next key for the hash.
 
 Verify that I<key> exists with the tied hash I<this>.
 
+The B<Tie::Hash> implementation is a stub that simply croaks.
+
 =item DELETE this, key
 
 Delete the key I<key> from the tied hash I<this>.