Ronald Oussoren came up with a concrete use case for wanting the interpreter to consider something a string, even if it isn't implemented with the default datastructure.
In https://mail.python.org/pipermail/python-ideas/2017-July/046407.html he writes: The reason I need to subclass str: in PyObjC I use a subclass of str to represent Objective-C strings (NSString/NSMutableString), and I need to keep track of the original value; mostly because there are some Objective-C APIs that use object identity. The worst part is that fully initialising the PyUnicodeObject fields often isn’t necessary as a lot of Objective-C strings aren’t used as strings in Python code. The PyUnicodeObject (via its leading PyASCIIObject member) currently uses 7 flag bits including 2 for kind. Would it be worth adding an 8th big to indicate that string is a virtual subclass, and that the internals should not be touched directly? (This would require changing some of the macros; at the time of PEP 393 it Martin ruled YAGNI ... but is this something that might reasonably be reconsidered, if someone did the work. Which I am considering, but not committing to.) -jJ _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
