Conjury - Introduction to Perl Conjury
Perl Conjury is a general purpose software construction framework. It's an alternative to the venerable make utility, but since it is written entirely in Perl, its capabilities extend to functions traditionally implemented using a text preprocessor to generate Makefile files, i.e. to configure for product variants.
The Perl Conjury system is a modular framework. The core software is very general. For example, to compile and link executable programs written in C or C++, you'll need the Conjury::C module-- bundled separately.
To use Perl Conjury, you will need Perl installed on your system. The command line utility is named cast, and it is a very short Perl script. It simply loads the Conjury::Core module, which does the heavy lifting: parsing the arguments and interpreting the files containing the "spells" for constructing your products from their sources.
Before the cast utility loads the Conjury::Core module, it first tries to add the top of the source file hierarchy to the Perl library search path. It does this by looking for a Conjury directory in the current directory, then its parent, that that directory's parent, all the way to the root of the current directory. Application specific modules for constructing the software should be placed in this directory and use the
You can carry all the general purpose Perl Conjury modules around with your source code, in whole or in part-- altering them for your own ends, if you like. Alternatively, you can just require that they be properly installed in the Perl site library. Your choice.
If you use the Conjury::Core module from the Perl Conjury distribution, then files named Conjury.pl, which you place in the same directories as the source, contain the code for constructing the products. These are written in Perl, and use modules from the Perl Conjury distribution as well as application-specific modules that are part of the source for the software under construction.
You'll need a Conjury.pl file at the top of your source file hierarchy, but you may use the
Conjury::Core::deferral function to create spells that defer action to other spells defined in Conjury.pl files you place in different locations in the source file hierarchy.
These files are Perl libraries (i.e. they are not executed directly, but rather loaded by the cast utility) that contain the code for constructing products from the source file with which they are associated.
This directory is found at the top of the source file hierarchy for the software under construction.
You're wondering-- why the name "Conjury" of all things? It's very simple.
If you have much experience owning and maintaining the code responsible for constructing a large, complex, cross-platform software system using make, you've probably seen all manner of horrific mechanisms for generating Makefile files using arcane translators and text processors. Some commercial software development environments even seem to perpetuate the problem to promote particular platforms.
These systems tend to combine the worst features of several languages together into the sort of Lovecraftian crawling horror that makes Perl seem like a harmless, fluffy bunny in comparison-- thus, the motivation for this work.
If you haven't yet, you really must see the sequence in that 1950's era animated feature film in which the most famous mouse in the world is "the sorcerer's apprentice," and he has used his master's magical arts to create an army of animated broomsticks to carry his water for him. It is the image of the mouse swirling around in the vortex of a whirlpool in the torrent of water his broomsticks dutifully create for him, while he is frantically thumbing through the documentation looking for the spell that will shut them all down, that the author had in mind when he was casting about for a name for this framework.
James Woodyatt <email@example.com>
The venerable make and its derivatives have inspired many attempts at better ways to approach basically the same problem. Perl Conjury is not the first, and it will doubtless not be the last. The author wishes to give due credit to the authors of jam and cons for the deep thinking that inspired this work-- in particular, the idea of journaling MD5 signatures to track which productions are up-to-date is a very good one, and the author slammed his forehead with his open palm very hard when he first saw it in the cons utility.
Copyright (c) 1999-2000 James H. Woodyatt. All rights reserved.
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