On 9/13/2018 8:04 PM, Victor Stinner wrote:
Le ven. 14 sept. 2018 à 00:09, Eric V. Smith <eric@trueblade.com> a écrit :
f'{type(obj)}' becomes type(obj).__format__(''), so you can return something other than __str__ or __repr__ does. It's only by convention that an object's __format__ returns __str__: it need not do so. What's New in Python 3.7 contains:
object.__format__(x, '') is now equivalent to str(x) rather than format(str(self), ''). (Contributed by Serhiy Storchaka in bpo-28974.) https://bugs.python.org/issue28974
Oh, I didn't know that a type is free to change this behavior: return something different than str(obj) if the format spec is an empty string.
True! That issue was specific to object.__format__, not any other classes implementation of __format__.
So are you suggesting to change type(obj).__format__('') to return the fully qualified name instead of repr(type)?
I'm not suggesting it, I'm saying it's possible. It indeed might be the most useful behavior.
So "%s" % type(obj) would use repr(), but "{}".format(type(obj)) and f"{type(obj)}" would return the fully qualified name?
"%s" % type(obj) would use str(), not repr. You could either: - keep with convention and have type(obj).__format__('') return type(obj).__str__(), while type(obj).__format__('#') (or what other char you want to use) return the qualname; or - just have type(obj).__format__('') return the qualname, if that's the more useful behavior. Eric