Method __enter__

tensorflow/python/eager/context.py:1492–1524

(self)

    self._stack = []

  def __enter__(self):
    ctx = self._ctx
    old_device_name = ctx.device_name
    old_device_spec = ctx.device_spec
    new_device_name = self._device_name
    cache_key = (old_device_name, new_device_name)
    try:
      new_device_name, new_device_spec = _device_parsing_cache[cache_key]
    except TypeError:
      # Error while trying to compute the cache key.
      raise ValueError("Expecting a string device name. Got %s(%s)" %
                       (type(new_device_name), new_device_name))
    except KeyError:
      # Handle a cache miss.
      if new_device_name is not None:
        if not isinstance(new_device_name, six.string_types):
          raise ValueError("Expecting a string device name. Got %s(%s)" %
                           (type(new_device_name), new_device_name))
        device_spec = pydev.DeviceSpec.from_string(new_device_name)
        if old_device_name:
          new_device_spec = copy.copy(old_device_spec)
        else:
          ctx.ensure_initialized()
          new_device_spec = pydev.DeviceSpec.from_string(
              ctx._context_devices[0])  # pylint: disable=protected-access
        new_device_spec = new_device_spec.make_merged_spec(device_spec)
      else:
        new_device_spec = pydev.DeviceSpec.from_string("")
      new_device_name = new_device_spec.to_string()
      _device_parsing_cache[cache_key] = (new_device_name, new_device_spec)

    ctx._set_device(new_device_name, new_device_spec)  # pylint: disable=protected-access
    self._stack.append((old_device_name, old_device_spec, new_device_spec))

  def __exit__(self, *ex_info):
    ctx = self._ctx