Extendable strings

pseudo_impl.py

#I dont have the knowledge to write this but i have the intrest in makeing it writen
#This is in no way complainat with the code of the pypy project and is just a sketch.

class Backend_string(W_object):
  _imutable_fields_ = ["_value"]
  def __init__(w_self, value):
    w_self._value = value
  
  def extend(w_self, w_other_real_string):
    magic_extend_function(w_self._value, w_other_real_string.unwrap(None))

class Real_string(W_object):
  __imutable_fields_ = ["_back", "_len"]
  def __init__(w_self, back, len):
    w_self._back = back
    w_self._len = len
  def unwrap(w_self, space):
    return w_self._back._value[:w_self._len]
  def extend(w_self, w_other)
    if w_self._len == len(w_self._back._value):
      w_self._back.extend(w_other)
      return Real_string(w_self._back, self._len + other._len)
    else:
      return Real_striing(Backend_string(w_self.unwrap(None) + w_other.unwrap(None)), self._len + other._len)