Hello,
On Tue, Jan 26, 2010 at 6:07 AM, msafiri <reich...@ifd.mavt.ethz.ch> wrote:
> Hello everyone,
> ticket #7207 deals with "from __future__" imports resulting in syntax
> errors in the SAGE notebook. The same is true when one tries to use
> cython from the command line e.g. via cython_create_local_so(). This
> is because the pyx_preparse() function in cython.py adds include
> statements to the beginning of the source code.
> This is probably not the correct platform to discuss bug-fixes, but
> this short piece of code solves the aforementioned problem (at least
> for my needs):
>
> # ------------ in cython.py:
>
> def parse_future_statements(s):
> """Looks for 'from __future__ import *' statements and moves them
> to the
> beginning of the string.
> """
>
> i = s.find('from __future__')
> if i != -1:
> j = s.find('\n', i)
> s = s[i:j+1] + s[0:i] + s[j+1:]
>
> return s
>
> # ---------------------------------
>
> The function "pyx_preparse()" in cython.py needs to call the above
> function just before it returns:
> s = parse_future_statements(s)
>
> Best,
> Johannes
>
> PS: Also, I've noticed that the source files to be "cythoned" really
> need to have .spxy extention. When using a .pyx file instead, the
> function "pyx_preparse()" will append the include directives in that
> very file (also, regardless of whether they have already been appended
> in a previous run).
>
> --
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>
My original patch was something like that, but William Stein pointed out
that it is easily tricked:
"""
from __future__ import division"""
[...]
will activate the code as well, which will result in a syntax error. I used
the AST parser to make sure no such thing happens, but I'm certain it is
possible to just use a less naive search.
--
Tim Joseph Dumol <tim (at) timdumol (dot) com>
http://timdumol.com
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