Function swap_item

Lib/test/support/__init__.py:1510–1538

Temporary swap out an item with a new object. Usage: with swap_item(obj, "item", 5): ... This will set obj["item"] to 5 for the duration of the with: block, restoring the old value at the end of the block. If `item` doesn't exist on `obj`, it will be

(obj, item, new_val)

@contextlib.contextmanager
def swap_item(obj, item, new_val):
    """Temporary swap out an item with a new object.

    Usage:
        with swap_item(obj, "item", 5):
            ...

        This will set obj["item"] to 5 for the duration of the with: block,
        restoring the old value at the end of the block. If `item` doesn't
        exist on `obj`, it will be created and then deleted at the end of the
        block.

        The old value (or None if it doesn't exist) will be assigned to the
        target of the "as" clause, if there is one.
    """
    if item in obj:
        real_val = obj[item]
        obj[item] = new_val
        try:
            yield real_val
        finally:
            obj[item] = real_val
    else:
        obj[item] = new_val
        try:
            yield
        finally:
            if item in obj:
                del obj[item]

def args_from_interpreter_flags():
    """Return a list of command-line arguments reproducing the current