Pyclips：将Clips类实例的多插槽设置为[]时出错

Question

我希望一个类实例的多槽位成为一个空列表。我不确定剪辑或pyclips中是否有错误，或者我做错了。

import clips

C = clips.BuildClass("C", "(is-a USER)(multislot s)")

i = clips.BuildInstance("test1", C)

#i.Slots['s'] = clips.Multifield([])          # error

i.Slots['s'] = []                             # error

#i.Slots['s'] = clips.Multifield(["1", "4"])  # no error

#i.Slots['s'] = ["1", "4"]                    # no error

print i.Slots["s"]

我收到此错误： _clips.ClipsError: C09: unable to understand argument

堆栈跟踪：

File "\\VBOXSVR\vagrant\return_empty_list_bug.py", line 6, in <module>

  i.Slots['s'] = [] # error

File "c:\Python27\Lib\site-packages\clips\_clips_wrap.py", line 175, in _WRAPPER

  return f(self, *args)

File "c:\Python27\Lib\site-packages\clips\_clips_wrap.py", line 269, in _WRAPPER

  return f(self, *newargs)

File "c:\Python27\Lib\site-packages\clips\_clips_wrap.py", line 2506, in __setitem__

  _c.directPutSlot(self.__instance, name, _py2cl(v))

_clips.ClipsError: C09: unable to understand argument