Tie::Array(3p) Perl Programmers Reference Guide Tie::Array(3p)

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)