.. -*- coding: utf-8 -*-

=================

 Version format.

=================

.. contents::

Feature set versioning.

=======================

Feature set versioning pretend to show how serious changes made according to

feature availability and how compatible these versions.

Marketing versioning.

=====================

Marketing versioning schema used for marketing, advertising, branding purpose.

It is usually inconsistent and can changed over the time.

Examples of marketing version schema:

 * Years.

 * Ancient gods.

 * Star/satellite/galactic names.

Look thread for GDB:

  http://www.cygwin.com/ml/gdb/2007-07/msg00061.html

There discussed:

 * Is it essential to update major version if significant change made for

   licence? Answer: **NO**!

   GPLv3 is a big deal spread out over the whole GNU project, but not a big deal

   for GDB in particular.

 * Is it right follow date version schema regardless major changes? Answer:

   **NO**!

   Many OS distribution encode year in versions but versions does not present

   featureset but package set instead.

Year as version name.

---------------------

If year used as version some people can decide that 2005 is too old and broken

if it used in 2007. So companies release product by leading year number. So in

2007 they release 2008 version.

Version name components.

========================

 * major

 * minor

 * patch (patchlevel), micro

 * rev (revision)

 * build

 * date

 * hotfix, fix

Version components usually combined in such group::

  major.minor.build

  major.minor.date

  major.minor.hotfix

  major.minor.hotfix.build

  major.minor.rev

  major.minor.rev.build

  major.current.age

Its conventional to have at least a major and minor number.

Prefixing version with a "v" seems to be less common.

Version in package/release name.

================================

::

  PACKAGE-MAJ.MIN.FIX.tar.gz   (Common style)

  PACKAGE-MAJ.MIN.FIX.zip

  PACKAGE-MAJ.MIN.FIX-DISTROFIX.tar.gz  (Cygwin style)

  PACKAGE_EPOCH:MAJ.MIN.FIX-DISTROFIX_ARCH.deb (Debian style)

From "Debian Policy Manual"::

  Package names must consist only of lower case letters (`a-z'), digits

  (`0-9'), plus (`+') and minus (`-') signs, and periods (`.').  They

  must be at least two characters long and must start with an

  alphanumeric character.

If you look carefully there are no any ``_`` (underscore) chars!! Also ``-`` is

portable char in file name accoding to POSIX.

Versioning for libraries/modules/components.

============================================

Major version component.

------------------------

Major number change means that fundamental change made in the architecture of

the system the new version is incompatible with the old one, upgrade between

versions is non-trivial, and any dependent of the prior version will require

code changes to upgrade to the new package.

Major number rare changed (this can take a lot of year).

Minor version component.

------------------------

Minor number change means that the new version is backward compatible with the

previous version but has significant enhancements over the previous version

(like new functionality or changed UI).

Functional enhancement releases. Contain new or significantly changed

functionality and/or layout.

New releases are usually only published several times a year or less.

Revision, micro, bugfix version component.

------------------------------------------

Revision number is updated whenever a bugfix or security patche is applied to

the build such that it doesn't bring a compatibility change or introduce newer

features.

Patches are released frequently (sometimes daily).

Milestone markers.

------------------

 * a (alpha) means new development is complete and code checkins are frozen.

   Alpha builds should work well enough to be testable.

 * b (beta) means most severe bugs are fixed and end users can start trying the

   release.

 * rc (release candidate) are believed to meet all of the criteria for release

   and can be installed on test instances of production systems.

Versioning for products.

========================

Versioning for products differ from versioning for libraries.

Product is a set of conponents that stalled to some versions. Components can be

switches as written for library versioning:

 * Any fix releases interchanged, greater version mean less bug count.

 * Any minor release interchanged with next minor releases.

 * Major release does not interchanged at all, switching from old to new require

   upgrade.

Product update vs upgrade.

--------------------------

Product update involve:

 * Replacing product executable files, resources files.

 * Config files and user data stay unchanged.

Product upgrade involve:

 * Replacing product executable files, resources files.

 * Config files and used data require modification and performed by upgrade

   scripts or manually by user (if this is ever possible).

 * Build number.

 * Build date.

 * VCS revision.

 * Branch-tag used.

 * Overnight build (Y/N).

 * QA tested (Y/N).

 * QA test results (Pass/Fail).

Stop your VCS hook to update version!

=====================================

Don't update version without human decision.

Why do not do this on success build:

 * You can have several build machine which may concurrently update version.

 * There does not exist tools for easy querying for status of build (as ok/fail,

   build configuration, date, coverage, lint checks, etc).

 * Some part of development team may not have permission for bumping version and

   after build they must revert some automatically updated files.

Why do not do this from pre-/post-commit hooks:

 * Some changes can only partially introduce feature/bugfix.

Version ordering formula.

=========================

Strongly recommend:

 * Numbers are not decimal fractions. They are integers separated by delimiters.

 * Only offically released versions of the program get version numbers.

   Development snapshots don't. Nor do test releases.

 * If the last component is zero, it may be omitted. Do not distinguish version

   X.Y from version X.Y.0.

 * Avoid using anything other than numbers in version numbers.

Debian version ordering formula.

--------------------------------

TODO

Semver version ordering formula.

--------------------------------

::

  if (A.major != B.major) return A.major > B.major;

  if (A.minor != B.minor) return A.minor > B.minor;

  if (A.patch != B.patch) return A.patch > B.patch;

  if (A.special == B.special) return 0;

  if (A.special == "") return 1;

  if (B.special == "") return -1;

  return A.special > B.special;

**NOTE** Accoding to this definition 1.0.1rc1 < 1.0.1rc10 < 1.0.1rc2 which is

non meaningful.

Odd/even numbering.

-------------------

Who use:

  GLib GTK+ Gimp GNOME Kaffe

Forms of compatibility.

=======================

Runtime of binary compatibility mean that binary can be swaped with another

version without breaking.

Compile time or source compatibility mean that supplied header/interfaces allow

successful compiling/linking.

Examples:

 * Change type of argument in method to more generic take source compatibility

   but break binary compatibility.

 * Adding new mothod to abstract class take binary compatibility but break

   compilation (unimplement method error).

File format compatibility.

Protocol compatibility.

Compatibility formula.

======================

Assume that app linked with new version of lib. Thus::

  is_compatible_with_old(old, new) {

    if (old.major != new.major) return 0;

    if (old.minor > new.minor) return 0;

    return 1;

  }

Assume that app linked with old version of lib. Thus::

  is_compatible_with_new(old, new) {

    if (old.major != new.major) return 0;

    return 1;

  }

Reference.

==========

  https://developer.mozilla.org/en/toolkit_version_format

                Toolkit version format

  http://apr.apache.org/versioning.html

                APR's Version Numbering

  http://semver.org/

                Semantic Versioning