


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


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


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


       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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