Gaps between Jython and Django
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Major problems
Jython does not support non-str keys in __dict__ right now. Jim Baker replaced the custom dictionary in PyStringMap with a HashMap (along Groves' earlier work). This change should resolve this problem. Try the [https://jython.svn.sourceforge.net/svnroot/jython/branches/modern/ modern] branch. Problem encountered in django/utils/_threading_local.py.
There is a problem with the algorithm deciding whether to call __str__ or __unicode__. More research is needed, but it affects the lazy string evaluation on which the Django i18n system relies (django/utils/functional.py), among other things.
I found that object.__unicode__ doesn't exist in CPython, and if it's removed from jython this works as expected. [https://sourceforge.net/tracker/?func=detail&atid=112867&aid=1800378&group_id=12867 bug] [https://sourceforge.net/tracker/?func=detail&atid=312867&aid=1800381&group_id=12867 patch] -- TristanKing
Something goes wrong with re.compile(u"([\u0080-\uffff])") in django/utils/text.py I think it is a lacking in our array implementation but this needs more investigation.
metaclasses need to know the __module__ of its classes [http://sourceforge.net/tracker/index.php?func=detail&aid=1781500&group_id=12867&atid=112867 bug] [http://sourceforge.net/tracker/index.php?func=detail&aid=1789137&group_id=12867&atid=312867 patch]
django/views/debug.py wants to know a function's __module__. functions don't have a __module__ attribute in jython yet. [http://sourceforge.net/tracker/index.php?func=detail&aid=1800472&group_id=12867&atid=312867 patch]
inspect.getargs() doesn't work.
That's because co_code isn't supported by PyTableCode.
But, co_code is used by getargs() only to discover anonymous tuple arguments. Commenting such section seems to be enough to get the other cases working.
workaround [https://dev.archer.edu.au/projects/kepler/svn/jython-django/trunk/jython-patches/co_code-workaround.patch patch]. just sets co_code = "". i haven't come across any problems for this inside django yet, but i'm sure it'll break other python code -- TristanKing
time module lacks strptime().
workaround [https://dev.archer.edu.au/projects/kepler/svn/jython-django/trunk/jython-patches/time-strptime.patch patch]. this is incomplete, untested, and not optimal but works for the django tutorial -- TristanKing
inspect.isclass(time) shouldn't return True [http://sourceforge.net/tracker/index.php?func=detail&aid=1786009&group_id=12867&atid=112867 bug]
Django [http://code.djangoproject.com/changeset/6194 works around this] until it's fixed.
Minor annoyances
slice should be a type, not a function. [http://sourceforge.net/tracker/index.php?func=detail&aid=1791931&group_id=12867&atid=112867 bug] [http://sourceforge.net/tracker/index.php?func=detail&aid=1798544&group_id=12867&atid=312867 patch]
PyBoolean.__tojava__ returns an Integer
It affects zxJDBC unless a DataHandler sets the right type of boolean parameters. Fortunately, JDBC30DataHandler does this thing, at least on my limited tests -- LeonardoSoto
Jython does not have __builtins__ as a module. Django adds "_" as a convenience method for calling gettext in django/conf/__init__.py.
According to the Python docs, __builtins__ is a implementation detail and shouldn't be used by portable applications, so it's a Django problem. (See note about __builtins__ here: http://docs.python.org/ref/naming.html)
Jython methods are not descriptors. It seems a implementation detail. [https://hg.leosoto.com/django.jythonport/diff/50371f2df15a/django/dispatch/saferef.py Here] is the relevant code and a potential fix from the Django side.
Jython classes which extend dict cannot be compared to a dict. [https://sourceforge.net/tracker/index.php?func=detail&aid=1804011&group_id=12867&atid=112867 bug] [https://dev.archer.edu.au/projects/kepler/changeset/149?format=diff&new=149 django patch]
Already Fixed
Jython does not have sys.stdout.isatty. Jython should get added to the exclusions around that call in django/core/management.py (win32 and 'Pocket PC' are already excluded).
Fixed in [http://code.djangoproject.com/changeset/6032 Django changeset 6032]
stringmap (or the __dict__ implementation) needs a pop(o) method.
Jython lists and tuples don't have __iter__ .
Fixed in [http://code.djangoproject.com/changeset/6211 Django changeset 6211]
Jython does not have os.getpid().
- Django workarounds it now.
Jython does not have os.W_OK needed in django/core/management.py. This probably will not be hard to add this since java.io.File has a canWrite().
os.chmod should be implemented too (After checking for write permissions, Django will try to change them if necessary).
- That's hard. Maybe Django shouldn't check for permissions if running on Jython.
- Django don't check or change file permissions when running on Jython now
The U (Universal newlines) flag for open() isn't recognized on Jython
- Unicode string interpolation doesn't work