python - How can I change the string object inside a string object? -

i'm trying create mutable string object subclassing str (unlike answer other question).

here's code far:

class mstr(str):      def __new__(self, s):          self.s = list(s)         return str.__new__(self, s)      def __getitem__(self, index):         return self.s[index]      def __setitem__(self, index, value):             self.s[index] = value      def __eq__(self, other):         return ''.join(self.s) == other      def __ne__(self, other):         return ''.join(self.s) != other      def __lt__(self, other):         return len(self.s) < len(other)      def __gt__(self, other):         return len(self.s) > len(other)      def __le__(self, other):         return len(self.s) <= len(other)      def __ge__(self, other):         return len(self.s) >= len(other)      def __add__(self, other):         return ''.join(self.s) + other      def __mul__(self, other):         return ''.join(self.s) * other      def __hash__(self):         return hash(''.join(self.s))      def __str__(self):         return ''.join(self.s)  def main():      s = mstr("hello ")     s[5] = " world!"     print(s)  if __name__ == '__main__':      main() 

by outputting example, it's easy fooled __ str __ return value:

hello world!  

it's easy fooled return value of __ add __ :

print(s + " bloody madness!") 

output:

hello world! bloody madness! 

but immutable truth revealed once pass mstr other argument of __ add __, example:

print(s + s) 

output:

hello world!hello  

removing methods:

class mstr(str):      def __new__(self, s):          self.s = list(s)         return str.__new__(self, s)      def __setitem__(self, index, value):             self.s[index] = value         self = ''.join(self.s) # foolish attepmt. 

output of print(s) "hello ".

so, how can change string object inside string object? mean, string actual , physical content stored in str or object or whatever? wherever is, want assign there.

it's in here:

typedef struct {     pyobject_var_head     long ob_shash;     int ob_sstate;     char ob_sval[1]; // part. (not 1 char.)      /* ... */ } pystringobject; 

unless want screw memory directly ctypes or something, can't @ it. if do screw it, weird things break, because assumption that data immutable isn't waived string subclasses.