The issue with your second version is

  In [1]: def init(shapename=None, **kwargs):
     ...:     pass
     ...: 

  In [2]: init(shapename='circle', **{'shapename': 'circle'})
  ---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  
  /home/teh/Desktop/<ipython console> in <module>()

  TypeError: init() got multiple values for keyword argument 'shapename'