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
# 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 DELETE and EXTEND
methods, 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
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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
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.
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.
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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'.
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>
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