+1
On Sep 20, 2009, at 11:25 PM, Chris McDonough wrote:
I'll try to digest some of this, currently I'm pretty clueless.
Personally, I find it a bit hard to get excited about Python 3 as a
web
application deployment platform. This is of course a personal
judgment (I
don't mean to slight Python 3) but at this point, I'll think I'll
probably be
writing software that targets 2.X exclusively for at least the next
five years.
Given this point of view, it would be extremely helpful if someone
could
explain to people with the same outlook why we should want to deal
with Unicode
strings in any WSGI specification.
WSGI is a fairly low-level protocol aimed at folks who need to
interface a
server to the outside world. The outside world (by its nature)
talks bytes. I
fear that any implied conversion of environment values and iterable
return
values to Unicode will actually eventually make things harder than
they are
now. I realize that it would make middleware implementors lives
harder to need
to deal in bytes. However, at this point, I also believe that
middleware kinda
should be hard. We have way too much middleware that shouldn't be
middleware
these days (some written by myself).
Anyway, for us slower (and maybe wrongly fearful) folks, could someone
summarize the benefits of having a WSGI specification that requires
Unicode.
Bonus points for an explanation that does not boil down to "it will be
compatible with Python 3".
- C
Armin Ronacher wrote:
Hello everybody,
Thanks to Graham Dumpleton and Robert Brewer there is some serious
progress on WSGI currently. I proposed a roadmap with some PEP
changes
now that need some input.
Summary:
WSGI 1.0 stays the same as PEP 0333 currently is
WSGI 1.1 becomes what Ian and I added to PEP 0333
WSGI 2.0 becomes a unicode powered version of WSGI 1.1
WSGI 3.0 becomes WSGI 2.0 just without start_response
WSGI 1.0 and 1.1 are byte based and nearly impossible to use on
Python
3 because of changes in the standard library that no longer work
with
a byte-only approach.
The PEPs themselves are here: http://bitbucket.org/ianb/wsgi-peps/
Neither the wording not the changes in there are anywhere near final.
Graham wrote down two questions he wants every major framework
developer
to be answered. These should guide the way to new WSGI standards:
1. Do we keep bytes everywhere forever in Python 2.X, or try to
introduce unicode there at all to at least mirror what changes
might
be made to make WSGI workable in Python 3.X?
2. Do we skip WSGI 1.X completely for Python 3.X and go straight to
WSGI 2.0 for Python 3.X?
I added a new question I think should be asked too:
3. Do we skip WSGI 2.0 as specified in the PEP and go straight to
WSGI 3.0 and drop start_response?
The following things became pretty clear when playing around with
various specifications on Python 3:
- Python 3 no longer implicitly converts between unicode and byte
strings. This covers comparisons, the regular expression engine,
all string functions and many modules in the stdlib.
- The Python 3 stdlib radically moved to unicode for non unicode
things
as well (the http servers, http clients, url handling etc.)
- A byte only version of WSGI appears unrealistic on Python 3
because
it would require server and middleware implementors to reimplement
parts of the standard library to work on bytes again.
- unicode support can be added for WSGI on both Python 2.x and
Python
3.x without removing functionality. Browsers are already doing
a similar encoding trick as proposed by Graham Dumpleton to handle
URLs.
- Python 2.x already accepts unicode strings for many things such as
URL handling thanks to the fact that unicode and byte strings are
surprisingly interchangeable.
- cgi.FieldStorage and some other parts is now totally broken on
Python 3 and should no longer be used in 3.0 and 3.1 because it
reads the response body into memory. This currently affects
WebOb, Pylons and TurboGears.
I sent this mail to every major framework / WSGI implementor so
that we
get input even if you're missing the discussion on web-sig.
Regards,
Armin
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