Tie::Array(3) Perl Programmers Reference Guide Tie::Array(3)NAMETie::Array - base class for tied arrays
SYNOPSIS
package 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 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
the perltie manpage 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" meth
ods 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 the
perltie manpage 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 the AnyDBM_File manpage
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 asso
ciated 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 associ
ated 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 asso
ciated 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 val
ues 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 off_
set.
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'.
Very little consideration has been given to the behaviour
of tied arrays when "$[" is not default value of zero.
AUTHOR
Nick Ing-Simmons <nik@tiuk.ti.com>
2001-02-22 perl v5.6.1 Tie::Array(3)
