This is Array::Lock.
Array::Lock is a set of subroutines to lock either the indexes value pairs of an array, or its indexes (size.) It can lock both to create an only readable array.
INSTALLATION
To install this module type the following:
perl Makefile.PL
make
make test
make install
DEPENDENCIES
Array::Lock requires perl version 5.7.3 to be useful, because of the Internals::SvREADONLY function.
COPYRIGHT AND LICENCE
Copyright 2003 by Gyan Kapur
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.