Issue 16167: Allow printing of str-derived classes (original) (raw)

Created on 2012-10-08 16:58 by Radu.Dan, last changed 2022-04-11 14:57 by admin. This issue is now closed.

Messages (4)
msg172396 - (view)	Author: Radu Dan (Radu.Dan)	Date: 2012-10-08 16:58
Classes that extend the builtin 'str' cannot be printed as is, and are automatically converted to string. #!/bin/env python class newstring(str): def __str__(self): return self a = newstring("hello world") print a Running this returns: Traceback (most recent call last): File "./test.py", line 7, in print a RuntimeError: print recursion Given that instances of 'str' are immutable, I see no reason why this should not work.
msg172407 - (view)	Author: Benjamin Peterson (benjamin.peterson) *	Date: 2012-10-08 20:01
Python 3.4.0a0 (default:8f048c8c855e, Oct 8 2012, 13:46:48) [GCC 4.5.4] on linux Type "help", "copyright", "credits" or "license" for more information. >>> class newstring(str): ... def __str__(self): ... return self ... >>> type(str(newstring())) <class '__main__.newstring'>
msg172408 - (view)	Author: Benjamin Peterson (benjamin.peterson) *	Date: 2012-10-08 20:02
And indeed >>> print(a) hello world
msg172409 - (view)	Author: Arfrever Frehtes Taifersar Arahesis (Arfrever) *	Date: 2012-10-08 20:15
Radu Dan: Printing of str-derived classes works in Python >=3.0, so you should just upgrade to newer version of Python. New features will not be backported to Python 2.