ScmPortError      147 src/error.c    SCM_DEFINE_BASE_CLASS(Scm_PortErrorClass, ScmPortError,
ScmPortError      247 src/error.c    static ScmObj porterror_port_get(ScmPortError *obj)
ScmPortError      252 src/error.c    static void porterror_port_set(ScmPortError *obj, ScmObj val)