#12205: rewrite conway polynomial spkg and code in Sage library to not use ZODB
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Reporter: was | Owner: was
Type: task | Status: new
Priority: major | Milestone: sage-5.6
Component: databases | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by SimonKing):
Replying to [comment:19 fbissey]:
> I think we have to stick with the dictionary format ...
As much as I understand, the "format" (in the sense of the "interface to
retrieve data") does not change. That's exactly the point: If you wanted
to inherit from dict, then you'd also have to have a `__setitem__` method
- but we don't want to set data in an interactive session. All what we
want is that during initialisation, data are obtained from a file, and
then the user can retrieve these data (which is granted by the
`__getitem__` method).
> ... since the code in sage is littered with calls to
!ConwayPolynomials()[p][n]
Would that be changed by the patch? Looking at the lines
{{{
def __getitem__(self, key):
try:
return self._store[key]
except KeyError, err:
try:
if isinstance(key, (tuple, list)):
if len(key) == 2:
return self._store[key[0]][key[1]]
except KeyError:
pass
raise err
}}}
it seems to me that `ConwayPolynomials()[p][n]` is still a possible syntax
(that's `return self._store[key]`), but ''in addition to the old syntax''
we now also allow the syntax `ConwayPolynomials()[p, n]` (that's `return
self._store[key[0]][key[1]]`).
> and changing the storage would imply changing an enormous amount of
code.
By "storage", I understand the format of the data stored in the .sobj file
containing the data base. I don't think that would be a problem, as long
as there is a function that is able to read old data and transforms it
into the new format.
> I trust that your python foo is way ahead of mine. I would never have
produced that getitem and didn't find any examples to do that with google.
That's in
[http://www.diveintopython.net/object_oriented_framework/special_class_methods.html
dive into python] or other Python introductions, or in the
[http://docs.python.org/2/reference/datamodel.html#special-method-names
Python documentation].
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12205#comment:22>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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