NAME
Array::Virtual - A perl extension providing disk based arrays implemented via tied hashes
VERSION
This documentation covers version 0.01 of Array::Virtual released July, 2001.
SYNOPSIS
use Array::Virtual;
tie @myarray, "Array::Virtual", "diskname", 0664;
push @myarray, "value";
my $stackpop = pop @myarray;
unshift @myarray, "value1";
my $queuefront = shift @myarray;
.
.
.
etc.DESCRIPTION
This module allows a user to tie an array to a disk file. The actual storage scheme is a hash tied via NDBM_File.
The module optimizes push, pop, shift and unshift for speed. For SPLICE, it uses the method inherited from Tie::Array. Splicing requires moving elements around. Since there is really no short cut for that, there is not a real way to optimize this routine, thus it is borrowed. Genuine DELETE is not yet supported. Attempting to call DELETE will result in the inherited croak from Tie::Array.
Once you issue a line like tie @myarray, "Virtual", "diskname", 0664; you may use @myarray just as you would any other array. The array will be stored in a file called diskname.array.db. Any path is preserved through the call, but .array.db is always appended. (This module puts on the array extension, NDBM_File puts on the .db extension.)
If there is already a file called diskname.array.db, it is opened and its contents are the same as the last time the disk array was used. If you want to purge the disk array, simply unlink diskname.array.db either inside or outside of perl.
If there is not a file called diskname.array.db, one is created with the given permissions if supplied (0644 by default).
DEPENDENCIES
This package inherits from Tie::Array from the standard distribution.
It uses the standard pragma strict.
In addition it uses Fcntl out of laziness, and NDBM_File out of necessity. Both of these are from the standard distribution.
NOTE WELL
This module never uses arrays in its implementation. It does not pay any attention to the deprecated $[ variable which allows arrays to begin at non-zero indices.
EXPORT
This module exports nothing. Everything in it is called transparently by the tie magician.
AUTHOR
Phil Crow crow@qns.com