def _getfield_is_safe(oldtype, newtype, offset):
    """ Checks safety of getfield for object arrays.

    As in _view_is_safe, we need to check that memory containing objects is not
    reinterpreted as a non-object datatype and vice versa.

    Parameters
    ----------
    oldtype : data-type
        Data type of the original ndarray.
    newtype : data-type
        Data type of the field being accessed by ndarray.getfield
    offset : int
        Offset of the field being accessed by ndarray.getfield

    Raises
    ------
    TypeError
        If the field access is invalid

    """
    if newtype.hasobject or oldtype.hasobject:
        if offset == 0 and newtype == oldtype:
            return
        if oldtype.names is not None:
            for name in oldtype.names:
                if oldtype.fields[name][1] == offset and oldtype.fields[name][0
                    ] == newtype:
                    return
        raise TypeError('Cannot get/set field of an object array')
    return
