========================================= Package "Data::Locations" Version 5.5 ========================================= This package is available for download either from my web site at http://www.engelschall.com/u/sb/download/ or from any CPAN (= "Comprehensive Perl Archive Network") mirror server: http://www.perl.com/CPAN/authors/id/S/ST/STBEY/ What's new in version 5.5: -------------------------- + Minor bugfixes and updates Legal issues: ------------- This package with all its parts is Copyright (c) 1997 - 2009 by Steffen Beyer. All rights reserved. This package is free software; you can use, modify and redistribute it under the same terms as Perl itself, i.e., under the terms of the "Artistic License" or the "GNU General Public License". Please refer to the files "Artistic.txt" and "GNU_GPL.txt" in this distribution, respectively, for details! Prerequisites: -------------- Perl version 5.004 or higher, and an ANSI C compiler. (!) ^^^^^^ Note that in order to compile Perl modules which contain C (and/or XS) code (such as this one), you always HAVE to use the very same compiler your Perl itself was compiled with. Many vendors nowadays ship their operating system already comprising a precompiled version of Perl. Many times the compilers used to compile this version of Perl are not available to or not usually used by the users of these operating systems. In such cases building this module (or any other Perl module containing C and/or XS code) will not work. You will either have to get the compiler which was used to compile Perl itself (see for example the section "Compiler:" in the output of the command "perl -V"), or to build your own Perl with the compiler of your choice (which also allows you to take advantage of the various compile- time switches Perl offers). Note that Sun Solaris and Red Hat Linux frequently were reported to suffer from this kind of problem. Moreover, you usually cannot build any modules under Windows 95/98 since the Win 95/98 command shell doesn't support the "&&" operator. You will need the Windows NT command shell ("cmd.exe") or the "4DOS" shell to be installed on your Windows 95/98 system first. Note that Windows NT, Windows 2000 and Windows XP are not affected and just work fine. I don't know about Windows Vista and Windows 7, however. Note that ActiveState provides precompiled binaries of this module for their Win32 port of Perl ("ActivePerl") on their web site, which you should be able to install simply by typing "ppm install Data-Locations" in your MS-DOS command shell (but note the "-" instead of "::" in the package name!). This also works under Windows 95/98 (!). If your firewall prevents "ppm" from downloading this package, you can also download it manually from http://www.activestate.com/ppmpackages/5.005/zips/ or http://www.activestate.com/ppmpackages/5.6/zips/. Follow the installation instructions included in the "zip" archive. Note to CPAN Testers: --------------------- After completion, version 5.5 of this module has already been tested successfully with the following configurations: Perl 5.005_03 - Windows XP SP3 & MS VC++ 6.0 (native Perl build) Perl 5.8.0 - Windows XP SP3 & MS VC++ 6.0 (native Perl build) Perl 5.10.1 - Windows XP SP3 & MS VC++ 6.0 (native Perl build) Perl 5.10.1 - FreeBSD 7.2-STABLE Installation: ------------- Please see the file "INSTALL.txt" in this distribution for instructions on how to install this package. It is essential that you read this file since one of the special cases described in it might apply to you, especially if you are running Perl under Windows. Changes over previous versions: ------------------------------- Please refer to the file "CHANGES.txt" in this distribution for a more detailed version history log. Documentation: -------------- The documentation of this package is included in POD format (= "Plain Old Documentation") in the file "Locations.pm" in this distribution, the human-readable markup-language standard for Perl documentation. By building this package, this documentation will automatically be converted into a man page, which will automatically be installed in your Perl tree for further reference through the installation process, where it can be accessed by the commands "man Data::Locations" (Unix) and "perldoc Data::Locations" (Unix and Win32 alike), for example. What does it do: ---------------- Data::Locations - magic insertion points in your data Did you already encounter the problem that you had to produce some data in a particular order, but that some piece of the data was still unavailable at the point in the sequence where it belonged and where it should have been produced? Did you also have to resort to cumbersome and tedious measures such as storing the first and the last part of your data separately, then producing the missing middle part, and finally putting it all together? In this simple case, involving only one deferred insertion, you might still put up with this solution. But if there is more than one deferred insertion, requiring the handling of many fragments of data, you will probably get annoyed and frustrated. You might even have to struggle with limitations of the file system of your operating system, or handling so many files might considerably slow down your application due to excessive file input/output. And if you don't know exactly beforehand how many deferred insertions there will be (if this depends dynamically on the data being processed), and/or if the pieces of data you need to insert need additional (nested) insertions themselves, things will get really tricky, messy and troublesome. In such a case you might wonder if there wasn't an elegant solution to this problem. This is where the "Data::Locations" module comes in: It handles such insertion points automatically for you, no matter how many and how deeply nested, purely in memory, requiring no (inherently slower) file input/output operations. (The underlying operating system will automatically take care if the amount of data becomes too large to be handled fully in memory, though, by swapping out unneeded parts.) Moreover, it also allows you to insert the same fragment of data into SEVERAL different places. This increases space efficiency because the same data is stored in memory only once, but used multiple times. Potential infinite recursion loops are detected automatically and refused. In order to better understand the underlying concept, think of "Data::Locations" as virtual files with almost random access: You can write data to them, you can say "reserve some space here which I will fill in later", and continue writing data. And you can of course also read from these virtual files, at any time, in order to see the data that a given virtual file currently contains. When you are finished filling in all the different parts of your virtual file, you can write out its contents in flattened form to a physical, real file this time, or process it otherwise (purely in memory, if you wish). You can also think of "Data::Locations" as bubbles and bubbles inside of other bubbles. You can inflate these bubbles in any arbitrary order you like through a straw (i.e., the bubble's object reference). Note that this module handles your data completely transparently, which means that you can use it equally well for text AND binary data. You might also be interested in knowing that this module and its concept have already been heavily used in the automatic code generation of large software projects. Credits: -------- Please refer to the file "CREDITS.txt" in this distribution for a list of contributors. Author's note: -------------- If you have any questions, suggestions or need any assistance, please let me know! Please do send feedback, this is essential for improving this module according to your needs! I hope you will find this module useful. Enjoy! Yours, -- Steffen Beyer http://www.engelschall.com/u/sb/ "There is enough for the need of everyone in this world, but not for the greed of everyone." - Mohandas Karamchand "Mahatma" Gandhi