Class Binding

dm_control/mjcf/physics.py:242–400

Binding between a mujoco.Physics and an mjcf.Element or a list of Elements. This object should normally be created by calling `physics.bind(element)` where `physics` is an instance of `mjcf.Physics`. See docstring for that function for details.

class Binding:
  """Binding between a mujoco.Physics and an mjcf.Element or a list of Elements.

  This object should normally be created by calling `physics.bind(element)`
  where `physics` is an instance of `mjcf.Physics`. See docstring for that
  function for details.
  """
  __slots__ = (
      '_attributes',
      '_physics',
      '_namespace',
      '_named_index',
      '_named_indexers',
      '_getattr_cache',
      '_array_index_cache',
  )

  def __init__(self, physics, namespace, named_index):
    try:
      self._attributes = _ATTRIBUTES[namespace]
    except KeyError:
      raise ValueError('elements of type {!r} cannot be bound to physics'
                       .format(namespace)) from None
    self._physics = physics
    self._namespace = namespace
    self._named_index = named_index
    self._named_indexers = {}
    self._getattr_cache = {}
    self._array_index_cache = {}

  def __dir__(self):
    return sorted(set(dir(type(self))).union(self._attributes))

  def _get_cached_named_indexer(self, name):
    named_indexer = self._named_indexers.get(name)
    if named_indexer is None:
      try:
        named_indexer = self._attributes[name].get_named_indexer(self._physics)
        self._named_indexers[name] = named_indexer
      except KeyError as e:
        raise AttributeError('bound element <{}> does not have attribute {!r}'
                             .format(self._namespace, name)) from e
    return named_indexer

  def _get_cached_array_and_index(self, name):
    """Returns `(array, index)` for a given field name."""
    named_indexer = self._get_cached_named_indexer(name)
    array = named_indexer._field  # pylint: disable=protected-access
    try:
      index = self._array_index_cache[name]
    except KeyError:
      index = named_indexer._convert_key(self._named_index)  # pylint: disable=protected-access
      self._array_index_cache[name] = index
    return array, index

  @property
  def element_id(self):
    """The ID number of this element within MuJoCo's data structures."""