[Python-Dev] str vs. unicode (original) (raw)

M.-A. Lemburg mal at egenix.com
Wed Jan 19 13:50:04 CET 2005

Nick Coghlan wrote:

M.-A. Lemburg wrote:

So if we fix str this would be a bugfix for 2.4.1. If we fix the rest, this would be a new feature for 2.5.

I have a feeling that we're better off with the bug fix than the new feature. str and unicode as well as the other hooks were specifically added for the type constructors to use. However, these were added at a time where sub-classing of types was not possible, so it's time now to reconsider whether this functionality should be extended to sub-classes as well. It seems oddly inconsistent though: """Define str to determine what your class returns for str(x). NOTE: This won't work if your class directly or indirectly inherits from str. If that is the case, you cannot alter the results of str(x).""" At present, most of the type constructors need the caveat, whereas str actually agrees with the simple explanation in the first line. Going back to PyUnicode, PyObjectUnicode's handling of subclasses of builtins is decidedly odd:

Those APIs were all written long before there were sub-classes of types.

Py> class C(str): ... def str(self): return "I am a string!" ... def unicode(self): return "I am not unicode!" ... Py> c = C() Py> str(c) 'I am a string!' Py> unicode(c) u''

Ah, looks as if the function needs a general overhaul :-)

This section should be do a PyString_CheckExact():

if (PyString_Check(v)) {
    Py_INCREF(v);
    	res = v;
     }

But before we start hacking the function, we need a general picture of what we think is right.

Note, BTW, that there is also a tp_str slot that serves as hook. The overall solution to this apparent mess should be consistent for all hooks (str, tp_str, unicode and a future tp_unicode).

-- Marc-Andre Lemburg eGenix.com

Professional Python Services directly from the Source (#1, Jan 10 2005)

Python/Zope Consulting and Support ... http://www.egenix.com/ mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/

::: Try mxODBC.Zope.DA for Windows,Linux,Solaris,FreeBSD for free ! ::::

More information about the Python-Dev mailing list