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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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* In particular, as a *record of decisions* about the project made by
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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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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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* 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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* 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 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.
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doc/purpose.txt
