8 # Pod documentation after __END__ below.
12 sub UNSHIFT { scalar shift->SPLICE(0,0,@_) }
13 sub SHIFT { shift->SPLICE(0,1) }
14 sub CLEAR { shift->STORESIZE(0) }
19 my $i = $obj->FETCHSIZE;
20 $obj->STORE($i++, shift) while (@_);
26 my $newsize = $obj->FETCHSIZE - 1;
30 $val = $obj->FETCH($newsize);
31 $obj->STORESIZE($newsize);
38 my $sz = $obj->FETCHSIZE;
39 my $off = (@_) ? shift : 0;
40 $off += $sz if ($off < 0);
41 my $len = (@_) ? shift : $sz - $off;
42 $len += $sz - $off if $len < 0;
44 for (my $i = 0; $i < $len; $i++) {
45 push(@result,$obj->FETCH($off+$i));
47 $off = $sz if $off > $sz;
48 $len -= $off + $len - $sz if $off + $len > $sz;
50 # Move items up to make room
54 for (my $i=$sz-1; $i >= $e; $i--) {
55 my $val = $obj->FETCH($i);
56 $obj->STORE($i+$d,$val);
60 # Move items down to close the gap
63 for (my $i=$off+$len; $i < $sz; $i++) {
64 my $val = $obj->FETCH($i);
65 $obj->STORE($i-$d,$val);
67 $obj->STORESIZE($sz-$d);
69 for (my $i=0; $i < @_; $i++) {
70 $obj->STORE($off+$i,$_[$i]);
72 return wantarray ? @result : pop @result;
77 croak "$pkg dosn't define an EXISTS method";
82 croak "$pkg dosn't define a DELETE method";
85 package Tie::StdArray;
89 sub TIEARRAY { bless [], $_[0] }
90 sub FETCHSIZE { scalar @{$_[0]} }
91 sub STORESIZE { $#{$_[0]} = $_[1]-1 }
92 sub STORE { $_[0]->[$_[1]] = $_[2] }
93 sub FETCH { $_[0]->[$_[1]] }
94 sub CLEAR { @{$_[0]} = () }
95 sub POP { pop(@{$_[0]}) }
96 sub PUSH { my $o = shift; push(@$o,@_) }
97 sub SHIFT { shift(@{$_[0]}) }
98 sub UNSHIFT { my $o = shift; unshift(@$o,@_) }
99 sub EXISTS { exists $_[0]->[$_[1]] }
100 sub DELETE { delete $_[0]->[$_[1]] }
105 my $sz = $ob->FETCHSIZE;
106 my $off = @_ ? shift : 0;
107 $off += $sz if $off < 0;
108 my $len = @_ ? shift : $sz-$off;
109 return splice(@$ob,$off,$len,@_);
118 Tie::Array - base class for tied arrays
124 @ISA = ('Tie::Array');
129 sub FETCHSIZE { ... }
131 sub STORE { ... } # mandatory if elements writeable
132 sub STORESIZE { ... } # mandatory if elements can be added/deleted
133 sub EXISTS { ... } # mandatory if exists() expected to work
134 sub DELETE { ... } # mandatory if delete() expected to work
136 # optional methods - for efficiency
149 @ISA = ('Tie::StdArray');
151 # all methods provided by default
155 $object = tie @somearray,Tie::NewArray;
156 $object = tie @somearray,Tie::StdArray;
157 $object = tie @somearray,Tie::NewStdArray;
163 This module provides methods for array-tying classes. See
164 L<perltie> for a list of the functions required in order to tie an array
165 to a package. The basic B<Tie::Array> package provides stub C<DESTROY>,
166 and C<EXTEND> methods that do nothing, stub C<DELETE> and C<EXISTS>
167 methods that croak() if the delete() or exists() builtins are ever called
168 on the tied array, and implementations of C<PUSH>, C<POP>, C<SHIFT>,
169 C<UNSHIFT>, C<SPLICE> and C<CLEAR> in terms of basic C<FETCH>, C<STORE>,
170 C<FETCHSIZE>, C<STORESIZE>.
172 The B<Tie::StdArray> package provides efficient methods required for tied arrays
173 which are implemented as blessed references to an "inner" perl array.
174 It inherits from B<Tie::Array>, and should cause tied arrays to behave exactly
175 like standard arrays, allowing for selective overloading of methods.
177 For developers wishing to write their own tied arrays, the required methods
178 are briefly defined below. See the L<perltie> section for more detailed
179 descriptive, as well as example code:
183 =item TIEARRAY classname, LIST
185 The class method is invoked by the command C<tie @array, classname>. Associates
186 an array instance with the specified class. C<LIST> would represent
187 additional arguments (along the lines of L<AnyDBM_File> and compatriots) needed
188 to complete the association. The method should return an object of a class which
189 provides the methods below.
191 =item STORE this, index, value
193 Store datum I<value> into I<index> for the tied array associated with
194 object I<this>. If this makes the array larger then
195 class's mapping of C<undef> should be returned for new positions.
197 =item FETCH this, index
199 Retrieve the datum in I<index> for the tied array associated with
204 Returns the total number of items in the tied array associated with
205 object I<this>. (Equivalent to C<scalar(@array)>).
207 =item STORESIZE this, count
209 Sets the total number of items in the tied array associated with
210 object I<this> to be I<count>. If this makes the array larger then
211 class's mapping of C<undef> should be returned for new positions.
212 If the array becomes smaller then entries beyond count should be
215 =item EXTEND this, count
217 Informative call that array is likely to grow to have I<count> entries.
218 Can be used to optimize allocation. This method need do nothing.
220 =item EXISTS this, key
222 Verify that the element at index I<key> exists in the tied array I<this>.
224 The B<Tie::Array> implementation is a stub that simply croaks.
226 =item DELETE this, key
228 Delete the element at index I<key> from the tied array I<this>.
230 The B<Tie::Array> implementation is a stub that simply croaks.
234 Clear (remove, delete, ...) all values from the tied array associated with
239 Normal object destructor method.
241 =item PUSH this, LIST
243 Append elements of LIST to the array.
247 Remove last element of the array and return it.
251 Remove the first element of the array (shifting other elements down)
254 =item UNSHIFT this, LIST
256 Insert LIST elements at the beginning of the array, moving existing elements
259 =item SPLICE this, offset, length, LIST
261 Perform the equivalent of C<splice> on the array.
263 I<offset> is optional and defaults to zero, negative values count back
264 from the end of the array.
266 I<length> is optional and defaults to rest of the array.
268 I<LIST> may be empty.
270 Returns a list of the original I<length> elements at I<offset>.
276 There is no support at present for tied @ISA. There is a potential conflict
277 between magic entries needed to notice setting of @ISA, and those needed to
280 Very little consideration has been given to the behaviour of tied arrays
281 when C<$[> is not default value of zero.
285 Nick Ing-Simmons E<lt>nik@tiuk.ti.comE<gt>