Distribution Organization

How Cat's Eye Technologies' software distributions are organized.

Release Engineering

Historically, Cat's Eye Technologies has usually identified each release of a software distribution with only a release number. The release number is really just the date that the software was released, formatted as YYYY.MMDD. Each of Y, M, and D is a single digit, so that it sorts nicely, even in a purely lexicographical sort order. In retrospect, YYYY.MM.DD might have been a more structurally consistent choice, but it's not as nicely symmetrical.

Using only the release date to identify releases mostly suffices for distributions like ours, which rarely have any maintenance needs warranting branches and such. But most of our distributions do contain implementations of programming languages, and these languages may or may not change between releases. For example, if we're just fixing bugs in a feature of the implementation, or clarifying the documentation or whatever, that's not a change to the language. But if all we use to identify it is a release number, you can't tell if it's a change to the language or not.

In addition, some of our distributions used a different convention, usually two numbers A.B which resembled a fraction in decimal notation: often B would be two digits (like 94) which did not count the number of minor releases since the last major release cycle, but rather tried to measure "how close" it was to the next major release cycle. Version numbers like this were sometimes also followed by an (essentially meaningless) letter.

Realizing what a mess this is, we have strived to revise our release identification system, as well as to make it more consistent.

With few exceptions, every distribution now carries both a version and a revision. The version consists of a major version number and a minor version number, in the format A.B, where A and B are both non-negative integers. The revision is the same as the old release number, that is, it is the date in YYYY.MMDD format. The version and revision are separated by hyphens, so a new-style "distfile" name typically looks like foo-1.3-2009.0116.zip (although we are by and large still providing only the legacy distfiles for download).

The rules for when these numbers change are as follows:

• If a new release of a distribution supports the same interface (syntax and semantics, API, protocol, or what have you) as the previous release of that distribution, then the version will be the same as the old distribution, but the revision will be different.
• If a new release of a distribution is more-or-less backwards-compatible with the previous release, then the major version will be the same, but the minor version and revision will be different.
• If a new release of a distribution is distinctly not backwards-compatible with the previous release, then the major version will be different, the minor version is typically reset to zero, and the revision will of course be the date of the release.

Filesystem Organization

This is a rough guide to how Cat's Eye Technologies' distributions are laid out. It is prescriptive, specifying how distributions should be laid out, but it is informed by the general pattern we're trying to find in our distributions. This guide is currently a work in progress and should not be considered complete yet.

Certain files in a distribution's root directory have standard meanings:

• README.markdown (preferred) or README or README.txt

  A short text (or preferably Markdown) document summarizing what the distribution is a distribution of, what sorts of files it contains, where to get the latest version of the distribution, and what other tools might be needed to use (run or build) the files found in it.

  READMEs for esolangs may describe the entire language. I'm not sure if this is a good practice or not. It started because Bitbucket would only HTMLify a Markdown file in its source viewer if it was the README, but now it will do that for every Markdown file, so there is less reason to put the whole language description here. Still, for some esolangs, this style seems to fit. (The only problem is that there isn't usually a good place to give the other info, like how to build and run the included implementations.)

• LICENSE or UNLICENSE

  A short text document explaining what license or licenses the content of the distribution is available under. The filename UNLICENSE is used instead if (and only if) the entire contents of the distribution are in the public domain.

• make.sh or Makefile

  A Bourne shell script which builds executables and related things from the sources included in the distribution. This may also be a Makefile, but Makefiles are usually put in the src directory. make.sh may just cd to that directory and run make.

• clean.sh

  A Bourne shell script to clean up after building, in lieu of a make clean command.

• test.sh

  A Bourne shell script which runs tests for the distribution. The tests can test anything they like, but should produce output which conforms to Portent format, which we haven't exactly defined yet, so don't worry about it. For now, an exit code of 0 means pass, anything else means failure.

Certain files in the root distribution directory have standard meanings as well:

• bin

  Where executables shoud be kept. Distributions should generally not contain native executables; the main exception to this rule is native executables for "legacy platforms" such as MS-DOS and Commodore 64 computers.

  Native executables may be written into the bin directory when they are built from other files in the distribution by e.g. make.sh.

  Distributions may contain non-native binary files intended to be executed, i.e. virtual machine code, and these will reside in bin. Java .class files are contained, under bin, in a directory tree matching the package names.

  Distributions may contain executable scripts. However, executable scripts which contain significant amounts of source code (i.e. ones that are not just little drivers or wrappers) should go in script rather than bin. They may in some cases be copied into bin upon build.

  Names of files in bin should not have extensions unless convention demands it. (That is, tool rather than tool.py, but tool.com is OK.)

• demo

  A directory of examples of how the contents of the distribution might be used. Somewhat interchangeable with eg, except that eg is primarily for example programs for a programming language (or configuration files, etc.) while demo contains demonstrations of how the tools (etc.) in the distribution might be used.

• dialect

  For distributions of programming (and other) languages, this is where related languages (usually too minor in variation to warrant their own distributions) are defined and implemented.

• disk

  Where disk images should be kept.

• doc

  Where documentation should be kept. Exceptions include README.markdown and LICENSE, which should be in the root directory.

  Images may be included in doc if they are part of the documentation (for example, diagrams) but if they are just screenshots, they should probably be elsewhere.

• ebin

  Distributions should not ship with pre-compile Erlang .beam files, but when they are built from the sources, they will go here. Erlang .app files may be contained here as well, but these are generally not all that useful, and mostly for decoration.

• eg

  Where examples should be kept, particularly example programs in distributions which contain implementations of programming languages. Somewhat interchangeable with demo, except that demo is primarily for demonstrations of how the tools (etc.) in the distribution might be used, while eg contains examples programs for a programming language (or configuration files, etc.)

• impl

  For distributions containing more than one implementation, this is where source code for the non-reference implementations should be kept. (The reference implementation's source should be in src.)

• priv

  Where data files for Erlang applications are kept.

• script

  Where executable scripts which have significant amount of code in them should be kept. (But if the script gets really large, it should probably be broken up into a driver script in bin which imports source modules from src.)

• src

  Where source code is kept. For distributions containing more than one implementation, this is where the reference implementation is kept; other implementations should probably be in impl instead.