pythonでファイルに書き込み

# -*- coding: utf-8 -*- 

import sys

class writer(object):

  def main(self):

       self.str = sys.argv[1]
       return self.str

  def file(self,name):
     
      open(name+".txt","w").write(self.str)

if __name__ == '__main__':

  obj = writer()
  obj.main()
  obj.file("writing_text")