GLEP:53

Abstract
This GLEP is a replacement of the keywording scheme from GLEP 22 The current use of keywords is retained in favour of 4-tuple keywords. This GLEP defines how current keywords are to be interpreted, and how future keywords should be constructed.

Motivation
Although the state of GLEP 22 is final, its keywording scheme was never propagated through the tree. In fact, 4-tuple keywords are not used at all. This GLEP defines a keywording scheme that is compatible with the scheme that is currently in use.

Rationale
The Gentoo/Alt project deals with different Operating Systems and architectures. Recently Gentoo/FreeBSD for Sparc was introduced after support for x86 platforms. This yielded in another new keyword. For these kind of platforms, a single field keyword is not enough to properly describe the OS and architecture. While four fields in a keyword are overkill, two fields in a keyword should be enough for everyone.

Backwards Compatibility
The proposed keywording scheme is fully compatible with the current situation of the portage tree, this in contrast to GLEP 22. The variables provided by GLEP 22 can't be extracted from the new keyword, but since GLEP 22-style keywords aren't in the tree at the moment, that is not a problem. The same information can be extracted from the  variable, if necessary. No modifications to ebuilds will have to be made.

Specification
Keywords will consist out of two parts separated by a hyphen. The left hand part of the keyword is the architecture, such as,   or. The right hand part indicates the operating system or distribution, such as,  ,   or. If the right hand part is omitted, it implies the operating system/distribution type is GNU/Linux. In such case the hyphen is also omitted. Examples of such keywords are  and. This is fully compatible with the current keywords used in the tree. Examples of OS/distributions for the right hand side of the keyword are:

(linux)         GNU/Linux (Gentoo biased, but not fixed) fbsd            FreeBSD macos           Apple Mac OS  solaris          Sun Solaris

Both architecture as well as OS/distribution are lower-case ASCII (alpha) numeric character sequences. A valid keyword matches the following expression:

Note that no limit on the length of both fields in the keyword are imposed. However, we cannot overemphasize our preference to keep keywords small and sensible.

Copyright
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/.