py3: an issue about dict iterators

[chapoton]

some sums complain when using python3

File "src/sage/combinat/crystals/multisegments.py", line 432, in sage.combinat.crystals.multisegments.InfinityCrystalOfMultisegments.Element.phi
Failed example:
    mg.f(1).phi(0)
Exception raised:
    Traceback (most recent call last):
      File "/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 557, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 967, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.combinat.crystals.multisegments.InfinityCrystalOfMultisegments.Element.phi[5]>", line 1, in <module>
        mg.f(Integer(1)).phi(Integer(0))
      File "/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/combinat/crystals/multisegments.py", line 436, in phi
        return self.epsilon(i) + self.weight().scalar(h[i])
      File "/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/combinat/root_system/weight_space.py", line 506, in scalar
        return BR.sum(self[i] * c for (i, c) in lambdacheck)
    TypeError: iter() returned non-iterator of type 'dict_items'

[chapoton]

New commits:

​52eee77

trac 24839 changing sums in weight_space

[chapoton]

this is not fixing the issue..

[chapoton]

Similar issue here under python3:

sage: d = DisjointSet(4)
sage: list(d)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-2-d0c0da2e41ad> in <module>()
----> 1 list(d)

TypeError: iter() returned non-iterator of type 'dict_values'

where the code is

return (<dict?>self.root_to_elements_dict()).itervalues()

that under python2 returns

sage: d = DisjointSet(4)
sage: iter(d)
<dictionary-valueiterator object at 0x7f0306d3f578>

[jdemeyer]

Sigh... I guess it has to be iter(dict.itervalues()) or yield from dict.itervalues() but I guess that the former will be faster.

[chapoton]

Eurk. Ugly enough, indeed. No hope that Cython could do that for us ?

How to find all instances of this problem ? Maybe by looking for pyx files containing both __iter__ and .iter[a-z] ?

[chapoton]

Potential list

crypto/boolean_function.pyx
libs/gap/element.pyx
algebras/letterplace/free_algebra_element_letterplace.pyx
algebras/lie_algebras/lie_algebra_element.pyx
plot/plot3d/index_face_set.pyx
ext/fast_eval.pyx
numerical/linear_functions.pyx
misc/weak_dict.pyx
rings/polynomial/polydict.pyx
rings/polynomial/laurent_polynomial.pyx
rings/polynomial/pbori.pyx
rings/polynomial/multi_polynomial.pyx
rings/polynomial/polynomial_element.pyx
rings/power_series_mpoly.pyx
sets/disjoint_set.pyx
quivers/algebra_elements.pyx
modules/with_basis/indexed_element.pyx
symbolic/expression.pyx

[jdemeyer]

There is no need to fix everything on one ticket. In any case, doctests will show what is broken.

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​bc7a60c

py3: fixing some iterators

[chapoton]

ok, let us content ourselves here with 3 changes

[chapoton]

bot is green

[chapoton]

ping ?