Hi Luis,
On 18 Mai, 00:45, Luis Finotti <luis.fino...@gmail.com> wrote:
> The problem is that it seems that it creates a loop, as in
> witt_element.py I need witt.py and vice-versa. That's why at the
> bottom of witt_element I had
>
> class RingOfWittVectors(RingOfWittVectors):
> # def _call_(self,data,parent,coerce=True):
> # return WittVector(data,parent,coerce)
> Element=WittVector
I see. But then, when you create your R, you should at least import
RingOfWittVectors from witt_element, not from witt. Not sure if that
would solve the problem. In any case, I think there are better ways of
doing the same. For example, if you want to do source inspection (like
R??), you wouldn't just like to see the few lines above, but you would
like to see the actual definition of the class (namely the one in
witt.py).
> If I follow your advice, I get:
>
> ImportError Traceback (most recent call last)
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/IPython/ipmaker.pyc
> in force_import(modname, force_reload)
> 61 reload(sys.modules[modname])
> 62 else:
> ---> 63 __import__(modname)
> 64
> 65
>
> /usr/local/sage-5.0.beta4/local/bin/ipy_profile_sage.py in <module>()
> 5 preparser(True)
> 6
> ----> 7 import sage.all_cmdline
> 8 sage.all_cmdline._init_cmdline(globals())
> 9
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/all_cmdline.py
> in <module>()
> 12 try:
> 13
> ---> 14 from sage.all import *
> 15 from sage.calculus.predefined import x
> 16 preparser(on=True)
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/all.py
> in <module>()
> 72 from sage.libs.all import *
> 73
> ---> 74 from sage.rings.all import *
> 75 from sage.matrix.all import *
> 76
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/rings/all.py
> in <module>()
> 72
> 73 # p-adic field
> ---> 74 from padics.all import *
> 75 from padics.padic_printing import _printer_defaults as padic_printing
> 76
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/rings/padics/all.py
> in <module>()
> 8 #from sage.rings.padics.witt import Big_Witt_Ring
> 9 #from sage.rings.padics.witt_element import Big_Witt_Vector
> ---> 10 from sage.rings.padics.witt import RingOfWittVectors
> 11 from sage.rings.padics.witt_element import WittVector
> 12
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/rings/padics/witt.py
> in <module>()
> 24 #from sage.structure.factory import UniqueFactory
> 25 from sage.categories.commutative_rings import CommutativeRings
> ---> 26 from witt_element import WittVector
> 27
> 28 class RingOfWittVectors(CommutativeRing):
>
> /usr/local/sage-5.0.beta4/local/lib/python2.7/site-packages/sage/rings/padics/witt_element.py
> in <module>()
> 23 from sage.structure.element import CommutativeRingElement
> 24 # from sage.structure.factory import UniqueFactory
> ---> 25 from sage.rings.padics.witt import RingOfWittVectors
> 26
> 27
>
> ImportError: cannot import name RingOfWittVectors
> Error importing ipy_profile_sage - perhaps you should run %upgrade?
> WARNING: Loading of ipy_profile_sage failed.
As David says, in order to avoid the circular import error, one should
try to break the import cycle. It seems to me that there is no need to
import RingOfWittVectors into witt_element.py, and so it would easily
possible to import WittVector into witt.py and use it to provide
RingOfWittVectors.Element.
Details. In witt_element.py, you use RingOfWittVectors in several
ways:
1.
def is_witt_vector(x):
return isinstance(x,RingOfWittVectors)
What is that supposed to do? If you want to test if x is a Witt
vector, shouldn't you test whether isinstance(x, WittVector)? The
RingOfWittVectors is certainly not a Witt vector by itself, isn't it?
And if that function really does the right thing, why don't you define
the function is_witt_vector in witt.py, rather than in
witt_element.py?
2. In WittVector.__init__:
if isinstance(data, RingOfWittVectors):
data = data._list
So, you really want to create a single vector out of some data
obtained from a *ring* of vectors?
Let R be a ring of witt vectors. With your current code, you seem to
allow
WittVector(R)
which is supposed to create a particular, canonical, element of R. Is
that intended (sorry, I don't know the mathematics behind Witt
vectors)? Then, why not work the other way around and define a method
of RingOfWittVectors returning that canonical element, perhaps even
with caching?
Hence, in witt.py:
class RingOfWittVectors(CommutativeRing):
Element = WittVector
...
@cached_method
def canonical_element(self):
return self(self._list)
(of course, you need to "from sage.misc.cachefunc import
cached_method")
It thus seems that you only need to import WittVector into witt.py,
but you don't need to import RingOfWittVectors into witt_element.py.
And, by the why, if you would import RingOfWittVectors in
WittVector.__init__ (not on module level), there would be a slow-down.
Best regards,
Simon
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