Tie::Array(3pm) Perl Programmers Reference Guide Tie::Array(3pm)
NAME
Tie::Array - base class for tied arrays
SYNOPSIS
package Tie::NewArray;
use Tie::Array;
@ISA = ('Tie::Array');
# mandatory methods
sub TIEARRAY { ... }
sub FETCH { ... }
sub FETCHSIZE { ... }
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 { ... }
sub PUSH { ... }
sub POP { ... }
sub SHIFT { ... }
sub UNSHIFT { ... }
sub SPLICE { ... }
sub EXTEND { ... }
sub DESTROY { ... }
package Tie::NewStdArray;
use Tie::Array;
@ISA = ('Tie::StdArray');
# all methods provided by default
package main;
$object = tie @somearray,'Tie::NewArray';
$object = tie @somearray,'Tie::StdArray';
$object = tie @somearray,'Tie::NewStdArray';
DESCRIPTION
This module provides methods for array-tying classes. See perltie for a
list of the functions required in order to tie an array to a package.
The basic Tie::Array package provides stub "DESTROY", and "EXTEND"
methods that do nothing, stub "DELETE" and "EXISTS" methods that
croak() if the delete() or exists() builtins are ever called on the
tied array, and implementations of "PUSH", "POP", "SHIFT", "UNSHIFT",
"SPLICE" and "CLEAR" in terms of basic "FETCH", "STORE", "FETCHSIZE",
"STORESIZE".
The Tie::StdArray package provides efficient methods required for tied
arrays which are implemented as blessed references to an "inner" perl
array. It inherits from Tie::Array, and should cause tied arrays to
behave exactly like standard arrays, allowing for selective overloading
of methods.
For developers wishing to write their own tied arrays, the required
methods are briefly defined below. See the perltie section for more
detailed descriptive, as well as example code:
TIEARRAY classname, LIST
The class method is invoked by the command "tie @array, classname".
Associates an array instance with the specified class. "LIST" would
represent additional arguments (along the lines of AnyDBM_File and
compatriots) needed to complete the association. The method should
return an object of a class which provides the methods below.
STORE this, index, value
Store datum value into index for the tied array associated with
object this. If this makes the array larger then class's mapping of
"undef" should be returned for new positions.
FETCH this, index
Retrieve the datum in index for the tied array associated with
object this.
FETCHSIZE this
Returns the total number of items in the tied array associated with
object this. (Equivalent to scalar(@array)).
STORESIZE this, count
Sets the total number of items in the tied array associated with
object this to be count. If this makes the array larger then
class's mapping of "undef" should be returned for new positions.
If the array becomes smaller then entries beyond count should be
deleted.
EXTEND this, count
Informative call that array is likely to grow to have count
entries. Can be used to optimize allocation. This method need do
nothing.
EXISTS this, key
Verify that the element at index key exists in the tied array this.
The Tie::Array implementation is a stub that simply croaks.
DELETE this, key
Delete the element at index key from the tied array this.
The Tie::Array implementation is a stub that simply croaks.
CLEAR this
Clear (remove, delete, ...) all values from the tied array
associated with object this.
DESTROY this
Normal object destructor method.
PUSH this, LIST
Append elements of LIST to the array.
POP this
Remove last element of the array and return it.
SHIFT this
Remove the first element of the array (shifting other elements
down) and return it.
UNSHIFT this, LIST
Insert LIST elements at the beginning of the array, moving existing
elements up to make room.
SPLICE this, offset, length, LIST
Perform the equivalent of "splice" on the array.
offset is optional and defaults to zero, negative values count back
from the end of the array.
length is optional and defaults to rest of the array.
LIST may be empty.
Returns a list of the original length elements at offset.
CAVEATS
There is no support at present for tied @ISA. There is a potential
conflict between magic entries needed to notice setting of @ISA, and
those needed to implement 'tie'.
AUTHOR
Nick Ing-Simmons <nik@tiuk.ti.com>
perl v5.38.2 2023-11-28 Tie::Array(3pm)
perl 5.38.2 - Generated Sat Dec 14 09:31:02 CST 2024