Issue 10660: format() to lower and uppercase (original) (raw)

Created on 2010-12-09 15:33 by Hervé Cauwelier, last changed 2022-04-11 14:57 by admin. This issue is now closed.

Messages (4)
msg123684 - (view)	Author: Hervé Cauwelier (Hervé Cauwelier)	Date: 2010-12-09 15:33
Hexadecimals can be formatted to lower and uppercase: >>> '{0:x}'.format(123) '7b' >>> '{0:X}'.format(123) '7B' I would like the same thing for strings: >>> '{0.lastname:u} {0.firstname}'.format(user) 'DOE John' I first thought using "S" for uppercase, but "s" is not available for lowercase. So I thought about "u" and "l". The alternative is to write: >>> '{0} {1}'.format(user.lastname.upper(), user.firstname) 'DOE John' But I find it less compact and elegant.
msg123685 - (view)	Author: R. David Murray (r.david.murray) *	Date: 2010-12-09 15:53
The format support is written specifically so that it is extensible. You can write your own string subclass that extends the formatting mini-language with whatever features you find useful. There are too many variations on what might be useful with regards to case transformations for this to be a sensible addition to the language itself. Much better that an application create use-case tailored facilities. (Note, by the way, that new features can only go in to 3.3 at this point.)
msg123686 - (view)	Author: Eric V. Smith (eric.smith) *	Date: 2010-12-09 16:53
I agree with David. Here's an example of using such a subclass. It extends the format string for strings to begin with an optional 'u' or 'l': ----------------------- class U(str): def __format__(self, fmt): if fmt[0] == 'u': s = self.upper() fmt = fmt[1:] elif fmt[0] == 'l': s = self.lower() fmt = fmt[1:] else: s = str(self) return s.__format__(fmt) name = 'Hervé Cauwelier' print('{0:u*^20} {0:l*^20} {0:*^20}'.format(U(name))) ----------------------- It produces: **HERVÉ CAUWELIER*** **hervé cauwelier*** **Hervé Cauwelier***
msg123720 - (view)	Author: Hervé Cauwelier (Hervé Cauwelier)	Date: 2010-12-10 08:37
Thanks for the example. The Python 2.7 documentation about the mini-language doesn't clearly state that it is extensible and how. we see examples of formatting but not of extending. Your example would be welcome in the documentation.