On Mon, Jul 13, 2009 at 8:14 AM, David Roe<r...@math.harvard.edu> wrote:
> Currently there are no classes in sage inheriting form PowerSeries other
> than PowerSeries_poly. But one could write a lazy power series class that
> used the same basic interface as PowerSeries, using lists or python
> functions, and define "class PowerSeries_lazy(PowerSeries)". I think that's
> the distinction.
Aha, that makes sense. So here's my problem: I'm working on trac 111,
i.e. change all the .copy() methods to __copy__(). Having done this
in power_series_poly.pyx, I am now getting a doctest failure in
power_series_ring_element.pyx, namely
sage: copy(f) is f # !!! ok since power series are immutable.
Expected:
True
Got:
False
This is because PowerSeries already has a __copy__() method which just
returns self, while the __copy__() method of PowerSeries_poly actually
returns a copy. The doctest is failing because f is a
PowerSeries_poly and hence the derived method is used.
So I'm not sure what to do. I cannot change the doctest because I
can't construct a PowerSeries which is not a PowerSeries_poly. My
thought now is to make PowerSeries.__copy__() return
NotImplementedError and have all derived classes override it.
Is this reasonable? Is there a better solution I don't see now?
Best,
Alex
--
Alex Ghitza -- Lecturer in Mathematics -- The University of Melbourne
-- Australia -- http://www.ms.unimelb.edu.au/~aghitza/
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