> On Sun, Sep 7, 2008 at 4:00 AM, Mike Hansen wrote:
>>
>> There is a patch up at
>> http://trac.sagemath.org/sage_trac/attachment/ticket/4036/trac_4036-2.patch
>> which improves conversions between Axiom and Sage. It defaults
>> to your unparsed input form if it can't find anything smarter to do.
>
On Sun, Sep 7, 2008 at 9:46 PM, Bill Page wrote:
> Excellent. I have applied this patch to
> sage-3.1.2.alpha4-sage.math-only-x86_64-Linux and with fricas-1.0.3
> installed. I tried a few things and so far it seems to work great!
> I'll have more time to test it thoroughly in the next 24 hours and let
> you know if I find any problems.
>
Mike,
So far everything is looking good to me in your patch. :-) I wonder if
there is still time to get it into the next release of Sage?
I have a question about the best way to add some new functionality to
the axiom interface. Maybe this is an interface design issue or maybe
it is just a Python question ...
In Sage we can call the Axiom 'guess' function (written by Martin
Rubey) to guess expressions for integer sequences. Eg.
sage: g=axiom('guess [1,3,5,7,9]')
sage: g
n 2
[[function= [[x ]f(x): (x - 2x + 1)f(x) - x - 1= 0],order= 0]]
sage: g.type()
List Record(function: Expression Integer,order: NonNegativeInteger)
-----------
As I understand the code in axiom.py, I can write:
sage: g[1]
n 2
[function= [[x ]f(x): (x - 2x + 1)f(x) - x - 1= 0],order= 0]
to return the first item in the Axiom List because __getitem__ is
defined in class AxiomElement. Right?
But now I have something of this type:
sage: g[1].type()
Record(function: Expression Integer,order: NonNegativeInteger)
The labels (e.g. 'function' and 'order' above) in an Axiom Record are
rather like attributes in Python. In Axiom I can write 'g(1).function'
and 'g(1).order'
sage: axiom(g.name()+'(1).function')
n 2
[[x ]f(x): (x - 2x + 1)f(x) - x - 1= 0]
sage: axiom(g.name()+'(1).order')
0
So I thought maybe I could also define
def __getattr__(self, attrname):
if attrname[:1] == "_":
raise AttributeError, attrname
if str(self.type()).startswith('Record'):
P = self.parent()
return P('%s.%s'%(self.name(), attrname))
else: raise AttributeError, attrname
in AxiomElement. And then in Sage write more naturally:
sage: g[1].function
n 2
[[x ]f(x): (x - 2x + 1)f(x) - x - 1= 0]
and I get the result I hoped for! :-) But when I write:
sage: g[1].order
<built-in method order of AxiomElement object at 0x2b30ac8cdaa0>
I do not get the expected result of 0. :-(
How can I persuade Sage to treat '.order' as a call to __getattr__ ?
As far as I understand, 'order' is a method inherited via
ExpectElement from RingElement. I do not understand why ExpectElement
subclasses RingElement. Why Ring? Anyway, in general I am looking for
a convenient and natural way to access elements of Axiom type Record
and Union.
Regards,
Bill Page.
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