metadata.list_size = -1;                  \
    metadata.type = attr_type;                \
    metadata.total_size = size_expr;          \
    break;

    SINGLE_CASE(kS, TF_ATTR_STRING, attr->s().length());
    SINGLE_CASE(kI, TF_ATTR_INT, -1);
    SINGLE_CASE(kF, TF_ATTR_FLOAT, -1);
    SINGLE_CASE(kB, TF_ATTR_BOOL, -1);
    SINGLE_CASE(kType, TF_ATTR_TYPE, -1);