#17814: Make calling a cached method independent of source code inspection
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Reporter: SimonKing | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.6
Component: distribution | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by SimonKing):
Here one can see how introspection enters:
{{{
sage: K=GF(5)
sage: C=type(K)
sage: C.factored_order
---------------------------------------------------------------------------
AttributeError Traceback (most recent call
last)
<ipython-input-4-d955bd892332> in <module>()
----> 1 C.factored_order
/home/king/Sage/git/sage/src/sage/misc/cachefunc.pyx in
sage.misc.cachefunc.CachedMethod.__get__
(build/cythonized/sage/misc/cachefunc.c:15452)()
2673 f = (<CachedFunction>self._cachedfunc).f
2674 if self.nargs==0:
-> 2675 args, varargs, keywords, defaults = sage_getargspec(f)
2676 if varargs is None and keywords is None and
len(args)<=1:
2677 self.nargs = 1
/home/king/Sage/git/sage/local/lib/python2.7/site-
packages/sage/misc/sageinspect.pyc in sage_getargspec(obj)
1394 except TypeError: # arg is not a code object
1395 # The above "hopefully" was wishful thinking:
-> 1396 return
inspect.ArgSpec(*_sage_getargspec_cython(sage_getsource(obj)))
1397 #return _sage_getargspec_from_ast(sage_getsource(obj))
1398 try:
/home/king/Sage/git/sage/local/lib/python2.7/site-
packages/sage/misc/sageinspect.pyc in _sage_getargspec_cython(source)
1006
1007 """
-> 1008 defpos = source.find('def ')
1009 assert defpos > -1, "The given source does not contain 'def'"
1010 s = source[defpos:].strip()
AttributeError: 'NoneType' object has no attribute 'find'
}}}
So: cached_method tries to determine the number of arguments. This is
because there is a special implementation for functions with no argument
(except `self`).
In other words, the wrong behaviour could be fixed by finding a way to get
the number of arguments (or better the argspec) of a cython function
without looking at its source code. I'll see if that's possible. So, the
fix will likely be in `sage.misc.sageinspect`, not in
`sage.misc.cachefunc`.
--
Ticket URL: <http://trac.sagemath.org/ticket/17814#comment:3>
Sage <http://www.sagemath.org>
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