You can also use the compiler module to create an abstract syntax tree and then traverse it and do the computation yourself. That way you get complete control of what you allow in the computation. Should be safer then the other options as the user code isn't actually run by the Python interpreter.
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You can also use the compiler module to create an abstract syntax tree and then traverse it and do the computation yourself. That way you get complete control of what you allow in the computation. Should be safer then the other options as the user code isn't actually run by the Python interpreter.
A nice example of how to do that is at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/364469.