This is the README file for NVDefined

NVDefined is an XS extension that implements Non-Vivifying defined and
exists functions (NVDefined and NVExists, respectively).

When used on a hash, the exists() and defined() functions will create
(vivify) entries in a hash in order to evaluate the function.

For instance, the code

    %a = (a => 1, b=> 2);
    print "Doesn't exist\n" unless exists($a{c});
    print "Also Doesn't exist\n" unless exists($a{c}->{d});
    print "Oh, my, not good\n" if exists($a{c});

will print out:

    Doesn't exist
    Also Doesn't exist
    Oh, my, not good

The NVDefined module provides two functions, NVDefined() and
NVExists(), which avoid this, at the cost of a slightly convoluted
syntax. Both functions take a reference to a hash, followed by a list
of descending keys defining the hash entry to be investigated.

To build and install this extension, the usual

    perl Makefile.PL
    make
    make test
    make install

will suffice.

NVDefined requires perl5.004, and is

Copyright(c) 1999 Brent B. Powers. All rights reserved. This program
is free software, you may redistribute it and/or modify it under the
same terms as Perl itself.