Developer Notes

These are the original docs written for pkgcore, detailing some of it’s architecture, intentions, and reasons behind certain designs.

Currently, the docs aren’t accurate- this will be corrected moving forward.

Right now they’re primarily useful from a background-info standpoint.

Content

• Rough TODO
• Changes
• Config use and implementation notes
  • Using the manager
  • Adding a configurable
  • Adding a config source
  • Implementation notes
• Checking the source out
• Installing pkgcore
  • Set PYTHONPATH
  • Registering plugins
  • Test pkgcore
  • Build extensions
• Ebuild EAPI
  • Version 0 (or undefined eapi, <=portage-2.0.52*)]
  • Version 1
  • Version 1+
• Feature (FEATURES) categories
  • relevant list of features
• Filesystem Operations
  • - File Deletion ( Removal )
  • - File Addition ( Installation )
  • - File Replacement ( Overwriting )
• Python Code Guidelines
  • Follow pep8, with following exemptions
  • Throw self with a NotImplementedError
  • Be aware of what the interpreter is actually doing
  • Don’t explicitly use has_key. Rely on the ‘in’ operator
  • Do not use [] or {} as default args in function/method definitions
  • Visible curried functions should have documentation
  • Unit testing
  • If it’s FS related code, it’s _usually_ cheaper to try then to ask then try
  • Catching Exceptions in python code (rather then cpython) isn’t cheap
  • cpython ‘leaks’ vars into local namespace for certain constructs
  • Unless you need to generate (and save) a range result, use xrange
  • Removals from a list aren’t cheap, especially left most
  • If you’re testing for None specifically, be aware of the ‘is’ operator
  • Deprecated/crappy modules
  • Know the exceptions that are thrown, and catch just those you’re interested in
  • tuples versus lists.
  • Don’t try to copy immutable instances (e.g. tuples/strings)
  • __del__ methods mess with garbage collection
  • A general point: python isn’t slow, your algorithm is
  • What’s up with __hash__ and dicts
  • __eq__ and __ne__
  • __eq__/__hash__ and subclassing
  • Exception subclassing
  • Memory debugging
• resolver
• resolver redesign
• config/use issues
• How to use guppy/heapy for tracking down memory usage
  • Tutorial of sorts
  • Extra stuff for c extension developers
• Plugins system
  • Goals
  • Using plugins
  • Adding plugins
  • Adding a plugin package
• Pkgcore/Portage differences
  • Disclaimer
• Tackling domain
• Testing
  • Testing for negative assertions
  • Using –coverage
• perl CPAN
• dpkg
• WARNING
• Introduction
  • Terminology
  • General design/idea/approach/requirements
  • Config design
  • config’s actions/operation
  • Objects/subsystems/stuff