Method for_fetch

tensorflow/python/client/session.py:253–284

Creates fetch mapper that handles the structure of `fetch`. The default graph must be the one from which we want to fetch values when this function is called. Args: fetch: An arbitrary fetch structure: singleton, list, tuple, namedtuple, or dict. Returns: An in

(fetch)

  @staticmethod
  def for_fetch(fetch):
    """Creates fetch mapper that handles the structure of `fetch`.

    The default graph must be the one from which we want to fetch values when
    this function is called.

    Args:
      fetch: An arbitrary fetch structure: singleton, list, tuple, namedtuple,
        or dict.

    Returns:
      An instance of a subclass of `_FetchMapper` that handles the shape.
    """
    if fetch is None:
      raise TypeError('Fetch argument %r has invalid type %r' %
                      (fetch, type(fetch)))
    elif isinstance(fetch, (list, tuple)):
      # NOTE(touts): This is also the code path for namedtuples.
      return _ListFetchMapper(fetch)
    elif isinstance(fetch, collections_abc.Mapping):
      return _DictFetchMapper(fetch)
    elif _is_attrs_instance(fetch):
      return _AttrsFetchMapper(fetch)
    else:
      # Look for a handler in the registered expansions.
      for tensor_type, fetch_fn, _, _ in _REGISTERED_EXPANSIONS:
        if isinstance(fetch, tensor_type):
          fetches, contraction_fn = fetch_fn(fetch)
          return _ElementFetchMapper(fetches, contraction_fn)
    # Did not find anything.
    raise TypeError('Fetch argument %r has invalid type %r' %
                    (fetch, type(fetch)))


class _ElementFetchMapper(_FetchMapper):