Method enter_context

Lib/contextlib.py:515–532

Enters the supplied context manager. If successful, also pushes its __exit__ method as a callback and returns the result of the __enter__ method.

(self, cm)

        return exit  # Allow use as a decorator.

    def enter_context(self, cm):
        """Enters the supplied context manager.

        If successful, also pushes its __exit__ method as a callback and
        returns the result of the __enter__ method.
        """
        # We look up the special methods on the type to match the with
        # statement.
        cls = type(cm)
        try:
            _enter = cls.__enter__
            _exit = cls.__exit__
        except AttributeError:
            raise TypeError(f"'{cls.__module__}.{cls.__qualname__}' object does "
                            f"not support the context manager protocol") from None
        result = _enter(cm)
        self._push_cm_exit(cm, _exit)
        return result

    def callback(self, callback, /, *args, **kwds):
        """Registers an arbitrary callback and arguments.