~bzr-pqm/bzr/bzr.dev

6 by mbp at sourcefrog
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What is the purpose of version control?
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There are several overlapping purposes:
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* Allowing concurrent development by several people.  Primarily,
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  helping resolve changes when they are integrated, but also making
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  each person aware of what the others have been doing, allowing them
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  to talk about changes, etc.
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* To allow different lines of development, with sensible
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  reintegration.  e.g. stable/development, or branches for
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  experimental features.
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* To record a history of development, so that you can find out why a
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  feature went in or who added it, or which releases might be affected
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  by a bug.
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* In particular, as a *record of decisions* about the project made by
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  the developers.
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* Help in writing a gloss on that history; not simply a record of
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  events but an explanation of what happened and why.  Such a record
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  may need to be written at several levels: a very detailed
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  explanation of changes to a function; a note that a bug was fixed
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  and why; and then a brief NEWS file for the whole release.  
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  While past events can never change, the intepretation placed upon
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  them may change, even after the event.  For example, even after a
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  release has gone out, one might want to go back and note that a bug
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  was actually fixed.
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  The system is helping the developers tell a story about the
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  development of the project.
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* As an aid to thinking about the project.  (Much as a personal
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  journal is not merely a record or even analysis of events, but also
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  a chance to reflect and to think of the future.)
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  People can review diffs, and then write a description of what
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  changed, and in doing so perhaps realize something else they should
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  do, or realize they made a mistake.  Making branches helps work out
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  the order of feature integration and the stability of different
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  lines of development.
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* As an 'undo' protection mechanism.  This is one reason why version
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  control can be useful on projects that have only a single developer
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  and never branch.
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* Incidentally, as a backup mechanism.  Version control systems,
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  particularly distributed systems, tend to cause code to exist on
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  several machines, which gives some protection against loss of any
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  single copy.  It's still a good idea to use a separate backup system
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  as well.
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* As a file-sharing mechanism: even with just a single developer and
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  line of development it can be useful to keep files synchronized
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  between several machines, which may not always be connected.
35 by Martin Pool
Notes from Steve Berczuk on purpose of SCM
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Steve Berczuk says__:
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__ http://www.bell-labs.com/cgi-user/OrgPatterns/OrgPatterns?ConfigurationManagementPatterns
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    A successful configuration management process allows:
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    * Developers to work together on a project, sharing common code.
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    * Developers to share development effort on a module.
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    * Developers to have access to the current stable (tested) version of a system.
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    * The ability to back up to a previous stable version (one of a number of NamedStableBases), of a system
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52 by mbp at sourcefrog
fixup doctest for new module structure
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    * The ability of a developer to checkpoint changes to a module and
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      to back off to a previous version of that module