mark florisson, 13.10.2011 13:52:
On 13 October 2011 12:44, Stefan Behnel wrote:
mark florisson, 13.10.2011 12:18:
On 13 October 2011 10:56, mark florisson wrote:
On 13 October 2011 10:53, Vitja Makarov wrote:
2011/10/13 Stefan Behnel:
Vitja Makarov, 13.10.2011 08:03:
I found that tempita bug goes away if you change language_level to 2.
There's no language level configured in Py2.4, which fails.
https://sage.math.washington.edu:8091/hudson/job/cython-devel-tests/48/BACKEND=c,PYVERSION=py24/console
No, I mean language level 3 is set at top of the Code.py, when it's
set to 2 Py2.4 build is okay.
Ah, it doesn't take unicode keyword arguments. That should be fixed.
Frankly, language level 3 is rather uncomfortable to deal with in
python 2(.4).
Well, without the parentheses, I presume ...
Ah, it appears only 2.7 eats unicode keyword arguments. I wonder why
the 2.5 and 2.6 builds didn't fail then.
Ah, right, I remember having to work around this in the C code at some
point. That's where the "identifier" kind of string in Cython originated from.
Any reason it's set to 3?
Mainly for performance reasons, especially in Python 2. Py3 code tends to
run faster in Cython due to more explicit semantics. In particular, we get
unicode content in and write unicode content out, so using unicode literals
in the source code right away saves a decoding step for each write or
interpolation of a literal string in Python 2. It won't make a difference
when running Cython in Python 3, but it saves a lot of unnecessary
processing cycles in Py2, even though the difference may not be substantial
over a complete run. It's just so convenient to switch the language level
and let that shave off a bunch of processing overhead that I didn't see a
reason not to do it.
I doubt that it'll make a functional difference, though, so if it works
better without that option, we may have to go back to Py2 compilation.
I see. Yeah it's sort of hard to fix, as I really need bytes in python
2 and really need unicode (str) in python 3, so I can neither write
'foo' nor b'foo' nor u'foo' with language level 3.
You can either pass the keyword arguments explicitly in the code or use
something like dict(foo=1) to get a dict of keyword arguments (also works
in Py2.4). Cython will turn the names into identifier strings, i.e. bytes
in Py2 and unicode in Py3, as required for keyword arguments.
BTW this is always a real problem in doctests too, as your bytestrings
will suddenly be printed as b'foo' in python 3, which will fail your
doctest. So to make it work you need to do explicit encoding/decoding
to make it work everywhere.
I usually either wrap them in a helper function or, as you say, put a
.decode() at the end. However, that fails to test explicitly for a byte
string in Py2, as .decode() also tends to work for ASCII-only unicode
strings there...
Let's hope that Py2 won't take a decade to die.
Stefan
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