Alternative to contextlib.nested with variable number of context managers

Question

We have code that invokes a variable number of context managers depending on runtime parameters:

from contextlib import nested, contextmanager

@contextmanag         


        

Answer 1

It's a little vexing that the python3 maintainers chose to break backwards compatibility, since implementing nested in terms of ExitStack is pretty straightforward:

try:
    from contextlib import nested  # Python 2
except ImportError:
    from contextlib import ExitStack, contextmanager

    @contextmanager
    def nested(*contexts):
        """
        Reimplementation of nested in python 3.
        """
        with ExitStack() as stack:
            for ctx in contexts:
                stack.enter_context(ctx)
            yield contexts