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ARCHITECTURE.md

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Introduction

This documentation is about the design of pacapt program. It describes how some components are connected to each other. And it's useful if you want to learn to contribute/improve the project.

pacapt is just small program, with a bunch of scripts. There is no such thing architecture; the name is inspired by the HN topic https://news.ycombinator.com/item?id=26048784

Components

pacapt

pacapt is our main program. It's a shell wrapper for many package managers on your system/OS, and now works perfectly in POSIX environment (except a few exceptions).

But we don't make changes in pacapt directly. The program is actually generated for every new release, and it's considered the stable version where everyone can easily download it (with curl or wget) on their system.

lib

The lib directory contains all shell scripts that would be combined into the main program pacapt. Each package manager has their own (separate) library file, for example lib/apk.sh contains all code used on Alpine-based system.

Other than that, there are a few important/essential files:

  • 00_core.sh: Contains DRY functions to be used in any other places.
  • 00_external.sh: Contains some script to support non-system package managers (pip, npm)
  • zz_main.sh: Contains an argument parser, shell switching (change from sh to bash if necessary), and invocations of the real back-end package manager.
  • The help contents are provided in a plain text file lib/help.txt.

tests

Contains all tests files written in a simple DSL. Some useful information about them can be read from tests/README.md. See real examples in tests/dpkg.txt (this is one of the richest test files we have).

bin

Contains two important scripts

  • compile.sh: Glue all files under lib directory and create the main program pacapt. It's also used to generate a development version of the script: Please check out make pacapt.dev for more details
  • gen_tests.sh: To deal with our tests DSL as mentioned in the section tests

The very tricky program bin/gen_stats.sh is used to generate the table of all supported operations that you see from the README.md. The algorithm was designed and implemented once and since then no further change has ever been made :D Well, it's so scary to touch that part, as long as it's working. It requires all methods in lib/ to follow a strict syntax which you can see from the code:

    <(
      # shellcheck disable=2016
      $GREP -hE "^${_PKGNAME}_[^ \\t]+\\(\\)" "$L" \
       | $AWK -F '(' '{print $1}'
    )

Don't worry. As long as you define a shell method as below, it's fine:

# method_name, follows by (), then a space, then a {
my_method() {
  : the body of the method
}

CI with github-action

Please visit the self-doc YAML file .github/workflows/ci.yaml.

History. Languages

The first implementation was submitted in 2010.

The project is using

  • Ruby
  • Perl
  • Bourne and Bourne-Again shell scripting language
  • Dockerfile
  • (GNU) parallel, awk, sed, grep
  • Dlang on some deprecated branches
  • its own DSL for test files
  • Markdown (Github format)
  • English

:P