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Ebuild file format

.. index::
   single: bash; conditions
   single: bash; variable reference
   single: indentation

Coding style

Source:QA
Reported:partially via repoman and pkgcheck

While Gentoo leaves most of the coding style choices to developers, there are a few rules which we try to enforce. Those are:

  • Always indent using a single tab for indentation level. Do not attempt to align, as it will not work with different tab widths.
  • Whenever using named variables, use bracketed variable form, i.e. ${foo} rather than $foo.
  • Use bash conditions [[ ... ]] rather than POSIX-ish [ ... ] or test builtin.

Rationale: the recommended constructs are less error-prone. Consistency avoids unnecessary changes when other developers edit the ebuild.

.. index:: eblit

Code must be contained within ebuild and eclasses

Source:QA
Reference:https://bugs.gentoo.org/612630
Reported:no

The ebuild code must be fully contained within .ebuild and .eclass files. It is forbidden to load additional ebuild code from other files via source, eval or any other possible method.

This affects historical use of 'eblits' to include phase functions from external files. The eblits used by the few affected packages were converted into eclasses.

Rationale: moving ebuild code to non-standard locations is against the principle of least surprise. It makes the maintenance harder, confuses other developers and tools that do not explicitly account for that possibility, including linting tools.

.. index:: homepage; variable

HOMEPAGE must not contain variables

Source:QA
Reported:by pkgcheck, highlighted as error by gentoo-syntax

The HOMEPAGE variable in ebuild must specify all the URIs verbatim, without referring to any variables. Variable references are allowed when setting generic values in eclasses.

Rationale: since homepage URIs do not contain dynamic parts (such as package versions), there is little advantage to using variables there. On the other hand, variables render the URIs unusable without preprocessing, breaking URI support in terminals and editors, as well as reducing the usefulness of plain tools such as grep.

.. index::
   pair: src uri; homepage

SRC_URI must not refer to HOMEPAGE

Source:QA
Reported:by pkgcheck

The SRC_URI variable in ebuild must not refer to ${HOMEPAGE}. If both overlap, the common part must be repeated verbatim.

Rationale: HOMEPAGE permits multiple entries by design, and developers are generally encouraged to add more helpful entries (e.g. project pages on PyPI, GitHub...). Making individual URIs incidentally depend on multi-valued variable having a single value goes against the principle of least surprise. Furthermore, it makes it hard to copy-paste part of the URI e.g. to investigate the directory index.