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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 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.

     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 <[email protected]>









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