Branching (version control)

Source: Wikipedia, the free encyclopedia.

Branching, in

directory tree
). Each object can thereafter be modified separately and in parallel so that the objects become different. In this context the objects are called branches. The users of the version control system can branch any branch.

Branches are also known as trees, streams or codelines. The originating branch is sometimes called the parent branch, the upstream branch (or simply upstream, especially if the branches are maintained by different organizations or individuals), or the backing stream.

Child branches are branches that have a parent; a branch without a parent is referred to as the trunk or the mainline.[1] The trunk is also sometimes loosely referred to as HEAD, but properly head refers not to a branch, but to the most recent commit on a given branch, and both the trunk and each named branch has its own head. The trunk is usually meant to be the base of a project on which development progresses. If developers are working exclusively on the trunk, it always contains the latest cutting-edge version of the project, but therefore may also be the most unstable version. Another approach is to split a branch off the trunk, implement changes in that branch and merge the changes back into the trunk when the branch has proven to be stable and working. Depending on development mode and commit policy the trunk may contain the most stable or the least stable or something-in-between version. Other terms for trunk include baseline, mainline, and master, though in some cases these are used with similar but distinct senses – see version control § Common terminology. Often main developer work takes place in the trunk and stable versions are branched, and occasional bug-fixes are merged from branches to the trunk. When development of future versions is done in non-trunk branches, it is usually done for projects that do not change often, or where a change is expected to take a long time to develop until it will be ready for incorporating in the trunk.

Merging

Branching generally implies the ability to later

relicensed under an incompatible license by a third party, or it attempts to serve a different purpose) is usually called a fork
.

Motivations for branching

Branches allow for parts of software to be developed in parallel.

merged
(resynchronized) after testing.

Development branch

A development branch or development tree of a piece of software is a version that is under

open source
community, the notion of release is typically metaphorical, since anyone can usually check out any desired version, whether it be in the development branch or not. Often, the version that will eventually become the next major version is called the development branch. However, there is often more than one subsequent version of the software under development at a given time.

Some revision control systems have specific jargon for the main development branch. For example, in

CVS, it is called the "MAIN" branch. Git uses "master" by default, although GitHub[4][5] and GitLab switched to "main" after the murder of George Floyd
. A more generic term is "trunk".

Shadow or magic branches

In CVSNT, a shadow or magic branch "shadows" changes made in the upstream branch, to make it easier to maintain small changes (cvc is an open-source package building system[citation needed] incorporating a revision-control system for packages produced by rPath.)

Distributed revision control

Repository clones

In

distributed revision control, the entire repository, with branches, may be copied and worked on further. Monotone (mtn), Mercurial (hg) and git call it "clone"; Bazaar calls it "branch".[citation needed
]

In some

distributed revision control systems, such as Darcs, there is no distinction made between repositories
and branches; in these systems, fetching a copy of a repository is equivalent to branching.

See also

References

  1. . Retrieved 2007-05-24.
  2. ^ Appleton, Brad; Berczuk, Stephen; Cabrera, Ralph; Orenstein, Robert (1998-02-08). "Streamed Lines: Branching Patterns for Parallel Software Development" (PDF). Hillside. Retrieved 2009-08-12.
  3. ^ Bailey, Derick (2009-07-15). "Part 1: Why". Branch-Per-Feature Source Control. Los techies. Retrieved 2009-08-12.
  4. ^ Wallen, Jack (2020-09-22). "GitHub to replace master with main starting in October: What developers need to do now". TechRepublic. Retrieved 2022-04-24.
  5. ^ Heinze, Carolyn (2020-11-24). "Why GitHub renamed its master branch to main". TheServerSide. Retrieved 2022-04-24.