[Python-Dev] Format strings, Unicode, and Py2.7: need clarification

[Hobson Lane]

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 <rodrigc at 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 at python.org
> https://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe: https://mail.python.org/mailman/options/python-dev/
> hobsonlane%40gmail.com
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20170517/c1d0351b/attachment.html>