Tab completion for elements of InfinitePolynomialRing

[ncohen]

Hello !!

I know nothing about Symbolics in Sage, but I will be using InfinitePolynomialRing? and I think the following code can be considered a bug. I create an expression using an element from InfinitePolynomialRing?, on which I use "Tab" to list its methods, some of them not being printed. Example :

sage: P.<x>=InfinitePolynomialRing(RR)
sage: e=x[1]+x[3]
sage: e.
e.abs                           e.footprint                     e.multiplicative_order          e.save
e.additive_order                e.is_nilpotent                  e.n                             e.squeezed
e.base_extend                   e.is_one                        e.order                         e.stretch
e.base_ring                     e.is_unit                       e.parent                        e.subs
e.category                      e.is_zero                       e.polynomial                    e.substitute
e.coefficient                   e.lc                            e.reduce                        e.symmetric_cancellation_order
e.db                            e.lm                            e.rename                        e.tail
e.dump                          e.lt                            e.reset_name                    e.variables
e.dumps                         e.max_index                     e.ring                          e.version
sage: e.constant_coefficient()
0.000000000000000

Besides, I do not understand why ( and I would really need it the other way ) inequalities on such expression return binaries instead of being kept symbolic :

sage: e<3
False

But this may be intentional, even though I do not like it :-)

Nathann

[burcin]

I don't see what the reported bug is. Note that the InfinitePolynomialRing has nothing to do with symbolics.

What is the problem in the first example?

If you want comparisons to remain symbolic, you should use symbolic variables that are declared with var().

For reference, the relevant thread where this was discussed is here:

​http://groups.google.com/group/sage-devel/browse_thread/thread/8a129481e1a947ad/f36a68f20242b6d7

[ncohen]

Hello !!!

Among the two remarks, the most important was the fact that the introspection in class InfinitePolynomialRing? seems to be flawed as some functions ( for example constant_coefficient() ) does not appear.. :-)

( I learnt some terminology since )

Nathann

[burcin]

AFAICT, introspection doesn't work simply because the given class doesn't have such a method. If you look at the file sage/rings/polynomial/infinite_polynomial_element.py, you'll see that a custom __getattr__ method is used to pass the call on to the real element self._p.

Maybe Mike knows a trick to make introspection work as well.

[SimonKing]

Hi Nathann!

Firstly, as was mentioned by Burcin, you mixed two completely different things, namely symbolics and commutative algebra. InfinitePolynomialRing? is about the latter. It isn't "misc" either, so, I am changing the component again.

Concerning e<3 returning True: This is clearly intentional and most certainly not a bug. It is essential to have polynomial rings ordered, if one wants to compute Gröbner bases -- and this is what InfinitePolynomialRing? is about.

Therefore I changed the Summary of the ticket (which was too unspecific anyway).

Concerning TAB completion: It is correct that the custom __getattr__ is to blame.

But I just learned something. Namely, if a class has a method _getAttributeNames that returns a list of strings, then these are used to do auto completion. Apparently methods __members__, __methods__ and trait_names also play a role, but I don't know which.

A possible solution is to implement _getAttributeNames so that it returns dir(underlying polynomial). I just tested: TAB-completion will then show both the genuine attributes of InfinitePolynomials? and the attributes inherited from usual polynomials.

But I don't think that this is a bug. So, I change the ticket type into "enhancement", and also added key words.

I will implement it (after dinner...) and post a patch.

Cheers, Simon

[SimonKing]

The dinner was good, and I hope the 3-line patch is as well.

I hope there is no need to rebase it, since I made it with sage-4.2.1.

With the patch, I get (on the command line):

sage: R.<t>=InfinitePolynomialRing(QQ)
sage: p=t[1]+3*t[4]
sage: p.<TAB>
p.abs                           p.jacobian_ideal
p.add_m_mul_q                   p.lc
p.additive_order                p.lcm
p.args                          p.lift
p.base_extend                   p.lm
p.base_ring                     p.lt
p.category                      p.map_coefficients
p.change_ring                   p.max_index
p.coefficient                   p.mod
p.coefficients                  p.monomial_coefficient
p.constant_coefficient          p.monomials
p.content                       p.multiplicative_order
p.db                            p.n
p.degree                        p.newton_polytope
p.degrees                       p.nvariables
p.derivative                    p.order
p.dict                          p.parent
p.divides                       p.polynomial
p.dump                          p.quo_rem
p.dumps                         p.reduce
p.exponents                     p.rename
p.factor                        p.reset_name
p.footprint                     p.resultant
--More--

It seems to me that this is what tab completion should do.

I understood that the new trac system is that I don't need to add [with patch, needs review] to the summary, but to tick "needs review"; correct me if I'm wrong.

[SimonKing]

Hi!

Now I learned that the method __members__ is used by dir()

It is a bit strange, since dir? explains that it would use a method __dir__ if it exists; but in fact it doesn't.

Anyway. With the new patch, one has both tab completion and introspection. Note that according to the original post, constant_coefficient, which is inherited from the underlying polynomial, did not appear.

sage: R.<t>=InfinitePolynomialRing(QQ)
sage: p=t[1]+3*t[4]
sage: L=dir(p)
sage: [X for X in L if X.startswith('c')]

['category',
 'change_ring',
 'coefficient',
 'coefficients',
 'constant_coefficient',
 'content']

And tab completion works as with the previous patch.

One concern though: How can one test tab completion? Note that the _getAttributeNames and __members__ methods have no doc test yet. How should it best look?

[SimonKing]

Introspection and tab completion(plus doc tests) for elements of InfinitePolynomialRing?

[SimonKing]

Hi!

Yet another patch (still under the same name). This time, I added some doc tests.

dir() provides a nice indirect doc test for __getattr__ (after all, this is where the introspection eventually got implemented). But I still don't know how to properly test tab completion. Hence, I call the relevant method directly, although it is underscore.

Cheers, Simon

[SimonKing]

Adding a better doc test for tab completion

[SimonKing]

The second patch (to be applied after the first) provides a nice indirect doc test for tab completion, according to William's advice at ​sage-devel.

[SimonKing]

I am currently overhauling the InfinitePolynomialRing? code, and I do so at ticket #7580.

My impression is that it would simplify the work flow if this ticket would be closed as unresolved, and that the implementation of tab completion should be part of #7580.

Also, I found that the method _getAttributeNames is not needed. It suffices for both tab completion and introspection if the __getattr__ method returns dir(underlying polynomial if the attribute __methods__ is requested.

I only wonder if it is dangerous to make p.__methods__ return things that aren't methods. However, when I googled for it, my impression was that the use of __methods__ in Python is not consistent. What is the Sage policy?

And do you agree that the work should be moved to #7580 ?

[malb]

Patch looks good, applies fine against alpha1, I have two doctest failures:

sage -t  devel/sage/sage/graphs/graph_generators.py # 2 doctests failed
sage -t  devel/sage/sage/server/misc.py # Segfault

The first one is a known alpha1 problem and the second one I cannot reproduce (it would also be rather unrelated).

[nthiery]

Replying to SimonKing:

Hi!

Now I learned that the method __members__ is used by dir()

It is a bit strange, since dir? explains that it would use a method __dir__ if it exists; but in fact it doesn't.

?

It actually works for me. In #7921, I added a dir to Element, which broke the current doctests in infinite polynomials. I just removed the members logic, and renamed _getAttributeNames into dir, and the doctests pass again (see patch on #7921). Could you have a look, and provide me with other tests if you think it could break something else in infinite polynomials?