23 lines
1.1 KiB
Text
23 lines
1.1 KiB
Text
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virtualenv is a tool to create isolated Python environments.
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The basic problem being addressed is one of dependencies and
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versions, and indirectly permissions. Imagine you have an application
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that needs version 1 of LibFoo, but another application requires
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version 2. How can you use both these applications? If you install
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everything into /usr/lib/python2.7/site-packages (or whatever your
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platform's standard location is), it's easy to end up in a situation
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where you unintentionally upgrade an application that shouldn't be
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upgraded.
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Or more generally, what if you want to install an application and
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leave it be? If an application works, any change in its libraries
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or the versions of those libraries can break the application.
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Also, what if you can't install packages into the global site-packages
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directory? For instance, on a shared host.
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In all these cases, virtualenv can help you. It creates an environment
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that has its own installation directories, that doesn't share
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libraries with other virtualenv environments (and optionally doesn't
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access the globally installed libraries either).
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