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pythoncontextmanager

Overriding multiple global variables with ContextManager

Is there a utility/pattern to override multiple global variables within a context in Python 2.7? IE something like

var1 = someval
var2 = someotherval
with my_context(var1=newval1, var2=newval2,...):
  print var1   # prints newval1
Solution

  • Yes, but the fact that it's unittest.mock.patch should tell you something about what this is intended to be used for:

    import unittest.mock

with unittest.mock.patch('module.thing', replacement_thing):
    do_whatever()

    If you want to patch several things in the same call, you can use unittest.mock.patch.multiple:

    from unittest.mock import patch

with patch.multiple(module, thing1=replacement_thing, thing2=other_thing):
    # module.thing1 and module.thing2 are now patched
    do_whatever()

    Just make sure none of the things you want to patch happen to collide with the argument names of that function (target, spec, create, spec_set, autospec, or new_callable). If they do, fall back to the regular patch.

    If you want to do this for non-unit-testing purposes, you may want to reconsider your design.

    If you're on Python 2 and unittest.mock isn't in the standard library, you can download the backport from PyPI. This one is called mock rather than unittest.mock.