Because `.format()` is a method on an instantiated `str` object in e and so must return the same type so additional str methods could be stacked on after it, like `.format(u'hi').decode()`. Whereas the % string interpolation is a binary operation, so, like addition, where the more general type can be used for the return value, analogous to `1 + 2.0` returning a float.
--Hobson (503) 974-6274 gh <https://github.com/hobson/> twtr <https://twitter.com/hobsonlane> li <https://www.linkedin.com/in/hobsonlane> g+ <http://plus.google.com/+HobsonLane/> so <http://stackoverflow.com/users/623735/hobs> On Wed, May 17, 2017 at 2:41 PM, Craig Rodrigues <rodr...@crodrigues.org> wrote: > Hi, > > While cleaning up some code during Python 2 -> Python 3 porting, > I switched some code to use str.format(), I found this behavor: > > Python 2.7 > ========= > a = "%s" % "hi" > b = "%s" % u"hi" > c = u"%s" % "hi" > d = "{}".format("hi") > e = "{}".format(u"hi") > f = u"{}".format("hi") > > type(a) == str > type(b) == unicode > type(c) == unicode > type(d) == str > type(e) == str > type(f) == unicode > > My intuition would lead me to believe that type(b) > and type(e) would be the same (unicode), but they are not. > The confusion for me is why is type(e) of type str, and not unicode? > > Can someone clarify this for me? > > I understand that in Python 3, all these cases are str, so it is not > as big a problem there, but I am trying to keep things working on > Python 2.7. > > Thanks. > -- > Craig > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > hobsonlane%40gmail.com > >
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