Tie::Array(3p) Perl Programmers Reference Guide Tie::Array(3p) #
Tie::Array(3p) Perl Programmers Reference Guide Tie::Array(3p)
NNAAMMEE #
Tie::Array - base class for tied arrays
SSYYNNOOPPSSIISS #
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';
DDEESSCCRRIIPPTTIIOONN #
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 TTiiee::::AArrrraayy package provides stub "DESTROY", and "EXTEND" methods
that do nothing, stub "DELETE" and "EXISTS" methods that ccrrooaakk(()) if the
ddeelleettee(()) or eexxiissttss(()) 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 TTiiee::::SSttddAArrrraayy package provides efficient methods required for tied
arrays which are implemented as blessed references to an "inner" perl
array. It inherits from TTiiee::::AArrrraayy, 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 _v_a_l_u_e into _i_n_d_e_x for the tied array associated with
object _t_h_i_s. 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 _i_n_d_e_x for the tied array associated with object
_t_h_i_s.
FETCHSIZE this
Returns the total number of items in the tied array associated with
object _t_h_i_s. (Equivalent to "scalar(@array)").
STORESIZE this, count
Sets the total number of items in the tied array associated with
object _t_h_i_s to be _c_o_u_n_t. 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 _c_o_u_n_t entries.
Can be used to optimize allocation. This method need do nothing.
EXISTS this, key
Verify that the element at index _k_e_y exists in the tied array _t_h_i_s.
The TTiiee::::AArrrraayy implementation is a stub that simply croaks.
DELETE this, key
Delete the element at index _k_e_y from the tied array _t_h_i_s.
The TTiiee::::AArrrraayy implementation is a stub that simply croaks.
CLEAR this
Clear (remove, delete, ...) all values from the tied array associated
with object _t_h_i_s.
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.
_o_f_f_s_e_t is optional and defaults to zero, negative values count back
from the end of the array.
_l_e_n_g_t_h is optional and defaults to rest of the array.
_L_I_S_T may be empty.
Returns a list of the original _l_e_n_g_t_h elements at _o_f_f_s_e_t.
CCAAVVEEAATTSS #
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'.
AAUUTTHHOORR #
Nick Ing-Simmons <nik@tiuk.ti.com>
perl v5.36.3 2019-02-13 Tie::Array(3p)