Tie::ShadowHash version 0.3
(Merge multiple data sources into a hash)
Copyright 1999 by Russ Allbery <
[email protected]>. This program is
free software; you may redistribute it and/or modify it under the same
terms as Perl itself.
INTRODUCTION
If you have a bunch of separate sources of data in the form of Perl
hashes, tied hashes (of whatever type, including on-disk databases tied
with DB_File, GDBM_File, or similar modules), or text files that you
want to turn into hashes, and you want to be able to query all of those
sources of data at once for a particular key without having to check
each one of them individually each time, this module is what you're
looking for. If you want to use a hash-like data source, even just one,
but make modifications to its data over the course of your program that
override its contents while your program runs but which don't have any
permanent effect on it, then this module may be what you're looking for.
Tie::ShadowHash lets you create a "shadow hash" that looks like a
regular Perl hash to your program but behind the scenes queries a whole
list of data sources. All the data sources underneath have to also
behave like Perl hashes, but that's the only constraint. They can be
regular Perl hashes or other tied hashes, including tied DB_File or
GDBM_File hashes or the like to access on-disk databases. All data
sources are treated as read-only; modifications to any data is stored in
the shadow hash itself, and subsequent accesses reflect any
modifications, but none of the data sources are changed.
See the POD documentation for complete details, features, and usage.
INSTALLATION
Follow the standard installation procedure for Perl modules, which is to
type the following commands:
perl Makefile.PL
make
make test
make install
You'll probably need to do the last as root. If instead you wish to
install the module by hand, simply copy it into a directory named Tie in
your Perl library directory.
CONTACTING ME
Please send any comments, bug reports, feature requests, or patches to
[email protected]. You may want to look over TODO before doing so to get
an idea of what I already have planned.
Please allow at least a month for me to respond to mail regarding this
module. I get at *least* 500 mail messages a day, and I'm afraid this
module is something that I only get a chance to work on once every few
months. I do intend to continue to maintain it, however, and I will get
back to you eventually.
