#22632 closed enhancement (fixed)
Cythonize CombinatorialFreeModuleElement
Reported by:  tscrim  Owned by:  

Priority:  major  Milestone:  sage8.0 
Component:  performance  Keywords:  days85 
Cc:  sagecombinat, nthiery, jdemeyer, chapoton  Merged in:  
Authors:  Travis Scrimshaw  Reviewers:  Nicolas M. Thiéry 
Report Upstream:  N/A  Work issues:  
Branch:  20cd0da (Commits)  Commit:  
Dependencies:  Stopgaps: 
Description
We move CombintorialFreeModuleElement
to its own class IndexedFreeModuleElement
and cythonize it for (future) speed gains.
Change History (78)
comment:1 Changed 10 months ago by
 Branch set to public/combinat/cythonize_CFM_element22632
 Commit set to e9186745d5df8cf7092e17103dee9c12b6b33ebf
 Status changed from new to needs_review
comment:2 Changed 10 months ago by
 Cc jdemeyer added
comment:3 Changed 10 months ago by
I Travis,
I'm curious, is there any performance gain. I had the impression that storing everything in python dict simply kills all possibilities of optimization ?
We discussed during past sage days, to reimplement combinatorial free modules, using arrays with a global dict for all object used only during input and output and not during linear algebra.
Florent
comment:4 Changed 10 months ago by
 Commit changed from e9186745d5df8cf7092e17103dee9c12b6b33ebf to 6b9d88b14b162c5d7ea88c3339896c3adc6e79da
Branch pushed to git repo; I updated commit sha1. New commits:
6b9d88b  Doing some additional tweaks.

comment:5 Changed 10 months ago by
There seems to be a little bit with doing basic operations:
sage: C = CombinatorialFreeModule(QQ, [1,2,3]) sage: x = sum(C.basis()) sage: %timeit [x + x for _ in range(1000)] 100 loops, best of 3: 2.57 ms per loop
vs old:
sage: C = CombinatorialFreeModule(QQ, [1,2,3]) sage: x = sum(C.basis()) sage: %timeit [x + x for _ in range(1000)] 100 loops, best of 3: 2.94 ms per loop
While it's not much, it is something like a 1015% speedup, but it is something likely to be called a significant number of times. It's even more so for scalar multiplication:
sage: s = SymmetricFunctions(ZZ).s() sage: x = s.an_element() sage: %timeit [4*x for _ in range(1000)] 100 loops, best of 3: 2.49 ms per loop
vs old:
sage: %timeit [4*x for _ in range(1000)] 100 loops, best of 3: 3.42 ms per loop
I might even be able to get some more speed if I am smarter in how we create the results of, e.g., _add_
.
comment:6 Changed 10 months ago by
 Commit changed from 6b9d88b14b162c5d7ea88c3339896c3adc6e79da to f1fcdd97670b9450f31e1230250dba8cde53c790
Branch pushed to git repo; I updated commit sha1. New commits:
f1fcdd9  Do not go through _from_dict but directly create an element.

comment:7 Changed 10 months ago by
That gives a very nice speed boost:
sage: C = CombinatorialFreeModule(QQ, [1,2,3]) ....: x = sum(C.basis()) ....: %timeit [x + x for _ in range(1000)] ....: 1000 loops, best of 3: 1.84 ms per loop sage: s = SymmetricFunctions(ZZ).s() sage: x = s.an_element() sage: %timeit [4*x for _ in range(1000)] 100 loops, best of 3: 2.05 ms per loop
Now those Python calls become relatively expensive, so we should avoid them.
comment:8 Changed 10 months ago by
 Cc chapoton added
Frédéric, I'm ccing you because you might want to note that I am taking care of the __cmp__
issue here as well.
comment:9 Changed 10 months ago by
 Status changed from needs_review to needs_work
many broken doctests..
comment:10 Changed 10 months ago by
 Commit changed from f1fcdd97670b9450f31e1230250dba8cde53c790 to 4ee3313767ce3b3be2f7b5a8f5938d0d6c3e0edc
comment:11 Changed 10 months ago by
 Status changed from needs_work to needs_review
Fixed the pickling issues and the other failures (incompatible signatures for _lmul_
and _rmul_
).
comment:12 Changed 10 months ago by
 Commit changed from 4ee3313767ce3b3be2f7b5a8f5938d0d6c3e0edc to d87735db11bdeab38d4932ca3b46abba8d4ba185
Branch pushed to git repo; I updated commit sha1. New commits:
d87735d  Fixed trivial doctest failure.

comment:13 Changed 9 months ago by
Patchbot is green (essentially, doctest failure is independent).
comment:14 Changed 8 months ago by
ping
comment:15 Changed 8 months ago by
diff git a/src/doc/en/thematic_tutorials/tutorialobjectsandclasses.rst b/src/doc/en/thematic_tutorials/tutorialobjectsandclasses.rst index 3f964bf..749ab5f 100644  a/src/doc/en/thematic_tutorials/tutorialobjectsandclasses.rst +++ b/src/doc/en/thematic_tutorials/tutorialobjectsandclasses.rst @@ 285,8 +285,7 @@ Some particular actions modify the data structure of ``el``:: sage: el.__class__ <class 'sage.combinat.free_module.CombinatorialFreeModule_with_category.element_class'> sage: el.__dict__  {'__custom_name': 'foo',  '_monomial_coefficients': {[1, 2, 3]: 1, [1, 3, 2]: 3}} + {'__custom_name': 'foo'}
Plausibly the explanation around that change needs to be updated a bit: there remains no "normal" attribute in this example. Maybe el.foo=1
could be issued before, and a comment added after that _monomial_coefficients
is a Cython attribute?
In general, this seems to be calling for changing the running example for this tutorial. The current one is a bit complicated. But that's for a later ticket.
comment:16 Changed 8 months ago by
@@ 242,7 +238,8 @@ class FreeAlgebraElement(AlgebraElement, CombinatorialFreeModuleElement): if self_on_left: return Factorization([(self, 1)]) * scalar return scalar * Factorization([(self, 1)])  return super(FreeAlgebraElement, self)._acted_upon_(scalar, self_on_left) + ret = super(FreeAlgebraElement, self)._acted_upon_(scalar, self_on_left) + return ret
What's the point?
comment:17 Changed 8 months ago by
As you notice, I am going through the changes. Up to those details, it looks good :)
comment:18 Changed 8 months ago by
About _divide_if_possible_
: since we are moving it anyway, shall we use the occasion to put it somewhere meaningful? Maybe as a method in EuclideanDomains?, as x._divide_if_possible(r)
, next to quo_rem
which it depends on?
comment:19 Changed 8 months ago by
I would move the comment about handling old pickles in the doc of
CombinatorialFreeModule.Element.__setstate__
, with a trac ref.
Please also add a brief comment and trac ref for the unpickle_override
at the end of the file.
comment:20 Changed 8 months ago by
Could you elaborate a bit why we need CombinatorialFreeModule.Element
to be a subclass of IndexedFreeModuleElement
? In particular, can you provide a minimal nonworking example?
comment:21 Changed 8 months ago by
# TODO: move the content of this class to CombinatorialFreeModule.Element and ModulesWithBasis.Element cdef class IndexedFreeModuleElement(Element):
The TODO could be updated :)
comment:22 Changed 8 months ago by
I am wondering whether the printing methods (_sorted_items_for_printing, latex, repr, asciiart, ...) should be moved to Modules.WithBasis.ElementMethods
. We are moving them anyway, and I believe they would be a reasonable default implementation. That would require providing a default value for parent._print_options
though, and deciding for a generic idiom to run through the items.
What do you think?
We could also keep that for a later ticket.
comment:23 Changed 8 months ago by
Instead of sage.modules.with_basis.indexed_free_module_element
, we could use the shorter sage.modules.with_basis.element
. That would be consistent with the nearby morphism
module.
I don't foresee other element classes in this module that would not be element classes for IndexedFreeModule
.
comment:24 Changed 8 months ago by
Users will have code importing CombinatorialFreeModuleElement
. We should support them with a deprecation alias "Please use CombinatorialFreeModule.Element
or IndexedFreeModuleElement
."
If we wan't to be even kinder to our users, helping them prepare for the next step, we could have sage.modules.with_basis.indexed_free_module.IndexedFreeModule
(or just .free_module.
?) be an alias for CombinatorialFreeModuleElement
. Then the above message warning would suggest IndexedFreeModule.Element
.
comment:25 Changed 8 months ago by
 Commit changed from d87735db11bdeab38d4932ca3b46abba8d4ba185 to f66cb0d2a72a70fb65d22bc115d75d4e85614899
Branch pushed to git repo; I updated commit sha1. New commits:
fbefa66  Merge branch 'public/combinat/cythonize_CFM_element22632' of git://trac.sagemath.org/sage into public/combinat/cythonize_CFM_element22632

68cdf67  Fixing things from testing.

99c99bf  Moving _divide_if_possible to EuclideanDomains.

cafb215  Remove map_coefficients call in __truediv__.

a8eeca6  Remove comment and deprecate CombinatorialFreeModuleElement.

6b96942  Rename indexed_free_module_element to indexed_element.

f66cb0d  Updating tutorial.

comment:26 Changed 8 months ago by
 Commit changed from f66cb0d2a72a70fb65d22bc115d75d4e85614899 to e0553bef39dbcee0dbaf72e6e38f9ad93f87d1c3
Branch pushed to git repo; I updated commit sha1. New commits:
e0553be  Adding comments about pickles.

comment:27 followup: ↓ 30 Changed 8 months ago by
 comment:15 I added a comment. Feel free to change. I also agree that a tutorial update should be done on a separate ticket.
 comment:16 I had separated that in order to track down a bug (4ee3313).
 comment:18 Good point. Done
 comment:19 I feel these are basically useless to repeating what the code makes (more) clear, but added.
 comment:20 This doesn't work with any subclasses where you need a
_mul_
from the category. Change it and try to multiply two symmetric group algebra elements for example:sage: SymmetricGroupAlgebra(QQ, 3) Symmetric group algebra of order 3 over Rational Field sage: prod(_.algebra_generators()) ... TypeError: 'NotImplementedType' object is not callable
There were also pickling issues.  comment:21 Done.
 comment:22 1 as that is a little too close to enforcing elements being printed as sums, which is not what we want.
 comment:23 I changed the file name to
indexed_element
aselement
is too generic for my tastes, but I left the class name the same.  comment:24 Done, but I slightly disagree with needing a deprecation because it was never imported into the global namespace. However, it was in the (public) doc, so it is good to have it. At this point, I think we should reference both and let the user decide.
comment:28 Changed 8 months ago by
 Commit changed from e0553bef39dbcee0dbaf72e6e38f9ad93f87d1c3 to b21fb167ab9562160ba5650e03ffd44a68be2c37
Branch pushed to git repo; I updated commit sha1. New commits:
b21fb16  22632: just a touch of polishing on the thematic tutorial change

comment:29 Changed 8 months ago by
 Commit changed from b21fb167ab9562160ba5650e03ffd44a68be2c37 to b13a870be54a27bfa1f2f71230256defc5b0d3a9
Branch pushed to git repo; I updated commit sha1. New commits:
b13a870  22632: use trac role instead of full url in doc

comment:30 in reply to: ↑ 27 Changed 8 months ago by
Replying to tscrim:
 comment:15 I added a comment. Feel free to change.
Thanks; I did a second pass on it. Good to go.
 comment:22 1 as that is a little too close to enforcing elements being printed as sums, which is not what we want.
I see it as merely providing a sane default which works generically but can be overridden at will. Anyway, that's admittedly out of scope for this ticket; we can decide later on.
 comment:23 I changed the file name to
indexed_element
aselement
is too generic for my tastes, but I left the class name the same.
Sounds good.
it was never imported into the global namespace. However, it was in the (public) doc, so it is good to have it.
Yup, exactly.
At this point, I think we should reference both and let the user decide.
Ok!
Out of curiosity, I am now going to have a quick look at the inheritance thing of comment:20. Other than that, it's good to go; thanks for all the hard work!
comment:31 Changed 8 months ago by
 Commit changed from b13a870be54a27bfa1f2f71230256defc5b0d3a9 to dec9bd65d49e91af6c662b658e838b1476306ec5
Branch pushed to git repo; I updated commit sha1. New commits:
dec9bd6  22632: make CombinatorialFreeModule.Element an alias (and not subclass) of IndexedFreeModuleElement

comment:32 Changed 8 months ago by
Advantage of the above commit:
 A bit simpler: no distinction anymore between
CFF.Element
andIndexedFreeModuleElement
. In particular there is no risk to have someone use directly IndexedFreeModule? without inheriting from it.  Avoids a double inheritance, with CFF.element_class deriving from CFF.Element itself deriving from
IndexedFreeModuleElement
Inconvenient:
 requires to override element_class
I believe it's worth it. What do you think?
comment:33 Changed 8 months ago by
Running tests here ...
comment:34 followup: ↓ 37 Changed 8 months ago by
I am not so convinced as it hides a fault in a nontrivial way; it something that we should not need to do. I do agree it is more simple. Nevertheless, one should typically use a subclass of the CFM.Element
when subclassing CFM
and needing a new element class if they want to use the same data structures. Although I don't think there is too much difference between our two hacks.
Also, in some ways it almost looks like you are moving the unpickling to a completely unrelated class since
register_unpickle_override("sage.combinat.free_module", "CombinatorialFreeModuleElement", CombinatorialFreeModule.Element)
If you want the __setstate__
in IndexedFreeModuleElement
, then this register_unpickle_override
should redirect to that.
comment:35 Changed 8 months ago by
 Commit changed from dec9bd65d49e91af6c662b658e838b1476306ec5 to 6665822c21ba3765553f3df12e640c5042958d0d
Branch pushed to git repo; I updated commit sha1. New commits:
6665822  22632: revert b13a870be: the trac link is in an error message!

comment:36 Changed 8 months ago by
 Commit changed from 6665822c21ba3765553f3df12e640c5042958d0d to 4a77584f43adbbc36b279591929a7a4370292ad3
comment:37 in reply to: ↑ 34 Changed 8 months ago by
Replying to tscrim:
I am not so convinced as it hides a fault in a nontrivial way; it something that we should not need to do. I do agree it is more simple. Nevertheless, one should typically use a subclass of the
CFM.Element
when subclassingCFM
and needing a new element class if they want to use the same data structures. Although I don't think there is too much difference between our two hacks.
Ok. I agree, it's minor anyway.
Also, in some ways it almost looks like you are moving the unpickling to a completely unrelated class since
register_unpickle_override("sage.combinat.free_module", "CombinatorialFreeModuleElement", CombinatorialFreeModule.Element)If you want the
__setstate__
inIndexedFreeModuleElement
, then thisregister_unpickle_override
should redirect to that.
Good point. Fixed. This prompted me to move the
register_unpickle_overide
next to IndexedFreeModuleElement
.
Sorry for the forcedpush; I had screwed up my commit just before.
Altogether, I believe this is good to go!
comment:38 Changed 8 months ago by
 Reviewers set to Nicolas M. Thiéry
 Status changed from needs_review to positive_review
comment:39 Changed 8 months ago by
Oh, I forgot about cafb215ba2b808e: what's the rationale for replacing .map_coefficients by what looks like hand written equivalent?
comment:40 Changed 8 months ago by
 Status changed from positive_review to needs_work
Oops, failing tests. Probably a triviality. Investigating.
comment:41 Changed 8 months ago by
 Commit changed from 4a77584f43adbbc36b279591929a7a4370292ad3 to 06a299e1c6d6734ec4930dc4f720dca5a4ead6ad
Branch pushed to git repo; I updated commit sha1. New commits:
06a299e  22632: fix typo in attribute name

comment:42 Changed 8 months ago by
It comes from the same commit :) Just a typo in _monomial_cofficients
. Fixed.
New commits:
06a299e  22632: fix typo in attribute name

comment:43 Changed 8 months ago by
 Status changed from needs_work to needs_review
comment:44 Changed 8 months ago by
sage t src/sage/homology/simplicial_complex.py # 1 doctest failed sage t src/sage/algebras/iwahori_hecke_algebra.py # 18 doctests failed sage t src/sage/calculus/calculus.py # 1 doctest failed sage t src/sage/categories/sets_cat.py # 1 doctest failed sage t src/sage/categories/hopf_algebras_with_basis.py # 1 doctest failed sage t src/sage/categories/algebras_with_basis.py # 1 doctest failed sage t src/sage/combinat/free_module.py # 1 doctest failed
Two types of failures:
... return type(self)(F, {k: c._divide_if_possible(x) File "sage/structure/element.pyx", line 459, in sage.structure.element.Element.__getattr__ (/opt/sage/src/build/cythonized/sage/structure/element.c:4256) return self.getattr_from_category(name) File "sage/structure/element.pyx", line 472, in sage.structure.element.Element.getattr_from_category (/opt/sage/src/build/cythonized/sage/structure/element.c:4365) return getattr_from_other_class(self, cls, name) File "sage/structure/misc.pyx", line 300, in sage.structure.misc.getattr_from_other_class (/opt/sage/src/build/cythonized/sage/structure/misc.c:1933) raise dummy_attribute_error AttributeError: 'sage.rings.polynomial.laurent_polynomial.LaurentPolynomial_univariate' object has no attribute '_divide_if_possible'
and trivial one about the element_class name. Working on the latter.
comment:45 followup: ↓ 46 Changed 8 months ago by
The former probably comes from a parent whose categories are not initialized.
comment:46 in reply to: ↑ 45 Changed 8 months ago by
Replying to nthiery:
The former probably comes from a parent whose categories are not initialized.
The problem comes from the fact that Laurent polynomials are not in Euclidean domains. There are also a number of natural rings that are not Euclidean domains, but have a quo_rem
that we could at least try this with (e.g., Z[x]). So I'm thinking of demoting it back down from the category.
comment:47 followup: ↓ 51 Changed 8 months ago by
I just found out the same :) Yeah, either demoting it back down, or lifting it up to Rings(). After all, it's a private method. So if it fails because it requires another method which is not implemented, that's ok. At least it will be easier to discover than if it's hidden in some random Python module. It's consistent with FreeModule?'s requirement of taking a ring as input.
comment:48 followup: ↓ 52 Changed 8 months ago by
For the other failure: it stems from the fact that the created element class's name is set to reflect that it's the element class of a given parent:
sage: A = Algebras(QQ).WithBasis().example() sage: A.element_class <class 'sage.combinat.free_module.FreeAlgebra_with_category.element_class'>
However the work is half baked, since the module is not set
accordingly: there is no class
sage.combinat.free_module.FreeAlgebra
; the module part comes from
CombinatorialFreeModuleElement.__module__
(I am running this example
without the ticket). With the ...Element
being moved, the module
part gets changed to sage.modules.with_basis.indexed_element
.
Two options:
 Not care and just update the doctests
 Improve the output of the element class by setting the module of the parent as module.
I just implemented the latter to check that it worked. The end result is more consistent for the user; here we get:
<class 'sage.categories.examples.algebras_with_basis.FreeAlgebra_with_category.element_class'>
However changing __module__
might possibly break some introspection
stuff (I checked A.element_class??
, and that was fine). It will also
require updating other doctests.
What do you think?
comment:49 Changed 8 months ago by
 Commit changed from 06a299e1c6d6734ec4930dc4f720dca5a4ead6ad to c889c4e9d791e692bec161f7c5bcc6afea8f4615
Branch pushed to git repo; I updated commit sha1. New commits:
c889c4e  22632: Fix the module part in dynamically created element classes, for consistency

comment:50 Changed 8 months ago by
 Commit changed from c889c4e9d791e692bec161f7c5bcc6afea8f4615 to 5a34041b0ab06dfbe1089698d50075c0525e066c
comment:51 in reply to: ↑ 47 Changed 8 months ago by
Replying to nthiery:
I just found out the same :) Yeah, either demoting it back down, or lifting it up to Rings(). After all, it's a private method. So if it fails because it requires another method which is not implemented, that's ok. At least it will be easier to discover than if it's hidden in some random Python module. It's consistent with FreeModule?'s requirement of taking a ring as input.
I think lifting it up to the category of Rings
works for now.
comment:52 in reply to: ↑ 48 Changed 8 months ago by
Replying to nthiery:
For the other failure: it stems from the fact that the created element class's name is set to reflect that it's the element class of a given ... Two options:
 Not care and just update the doctests
 Improve the output of the element class by setting the module of the parent as module.
What do you think?
This seems to be a can of worms. :/ Although I would rather have the latter as well since it is a more proper fix. Since you've done it, we might as well keep it.
comment:53 Changed 8 months ago by
Ok; tests running here. Let's keep it only if there are just trivial doctests updates.
comment:54 Changed 8 months ago by
 Commit changed from 5a34041b0ab06dfbe1089698d50075c0525e066c to 4c63230f181aebf2b24ea6bd14d9868cce3dbef8
comment:55 Changed 8 months ago by
 Commit changed from 4c63230f181aebf2b24ea6bd14d9868cce3dbef8 to b11d26e6fbd0fa2668b242e13c006fe57510ebb2
Branch pushed to git repo; I updated commit sha1. New commits:
b11d26e  22632: trivial indentation fix

comment:56 Changed 8 months ago by
All doctests updates were trivial. Being tired, I may have missed a few. Please rerun the tests, and if all goes well, or there just are some more trivial doctest updates, you can set a positive review on my behalf.
Cheers
comment:57 Changed 8 months ago by
 Status changed from needs_review to positive_review
Tests pass for me too.
comment:58 Changed 8 months ago by
Thank you for the review.
comment:59 Changed 8 months ago by
My pleasure! I am glad this is done.
comment:60 Changed 8 months ago by
 Status changed from positive_review to needs_work
PDF docs dont build
comment:61 Changed 8 months ago by
Compiling the doc here ...
comment:62 Changed 8 months ago by
 Commit changed from b11d26e6fbd0fa2668b242e13c006fe57510ebb2 to 20cd0dafdc07517145c3d8a20cbf8baa08e334dc
Branch pushed to git repo; I updated commit sha1. New commits:
20cd0da  22632: fixed ReST typo preventing the pdf doc compilation

comment:63 Changed 8 months ago by
Arg, the exact same _mul_
mistake has appeared a couple days ago in some other ticket.
I'll set back a positive review when the pdf doc compilation will be finished, in case there wouldbe something else.
Thanks Volker for reporting ...
comment:64 Changed 8 months ago by
The only other error I get is:
[docpdf] l.42 \addto [docpdf] \extrasmagyar{\def\pageautorefname{page}}
And I assume this is related to an outdate latex install on my machine:
[docpdf] Package sphinx Warning: [docpdf] ******** ERROR !! PLEASE UPDATE titlesec.sty !!******** [docpdf] ******** THIS VERSION SWALLOWS SECTION NUMBERS.********.
So, putting this back to positive review. Travis, can you double check things compile on your machine?
comment:65 Changed 8 months ago by
 Status changed from needs_work to positive_review
comment:66 Changed 8 months ago by
pdf doc built for me too.
comment:67 Changed 8 months ago by
 Branch changed from public/combinat/cythonize_CFM_element22632 to 20cd0dafdc07517145c3d8a20cbf8baa08e334dc
 Resolution set to fixed
 Status changed from positive_review to closed
comment:68 Changed 6 months ago by
 Commit 20cd0dafdc07517145c3d8a20cbf8baa08e334dc deleted
Question: what exactly is the purpose of the condition involving is_extension_type()
in __make_element_class__
?
I am trying to understand how/why is_extension_type
is used in Sage. In other places in parent.pyx
, it is to determine whether __class__
can be assigned to. But in __make_element_class__
, it's not so clear to me.
(I know it's not directly related to this ticket, but git blame
brought me here since this ticket made changes to __make_element_class__
)
comment:69 followup: ↓ 70 Changed 6 months ago by
Hi Jeroen!
In make_element_class
, we need to decide how elements shall inherit from categories: either by subclassing
P.Element
(or the relevant class), or by using the
getattr
trick. The current rule is to subclass if
P.Element
is a Python class, and use
getattr
if
P.Element
is an extension type.
is_extension_type
is used to do the test.
comment:70 in reply to: ↑ 69 ; followup: ↓ 71 Changed 6 months ago by
Thanks. That answers the factual question ("how is it done?") but not really the reason.
There are many differences between Python and Cython classes and I'm trying to understand which property matters here. I am asking because I tried to always use the dynamic class (using inherit=True
in __make_element_class__
even for Cython element classes) and there is not much that breaks.
These are the main differences between Python and Cython classes that I can think of:
 The fact that
__class__
can be assigned to for Python classes (I don't think this is the reason here)
 The fact that Python classes have a
__dict__
(this is no longer true: Python classes with__slots__
don't have a__dict__
by default and Cython classes do support__dict__
if you declare it as attribute)
 The fact that Python classes always support multiple inheritance, which may or may not work for Cython classes
 Pickling (although Cython 0.26 does support pickling of Cython classes)
 Various performance differences
 ...
comment:71 in reply to: ↑ 70 Changed 6 months ago by
Replying to jdemeyer:
I am asking because I tried to always use the dynamic class (using
inherit=True
in__make_element_class__
even for Cython element classes) and there is not much that breaks.
To elaborate on this: after making this change

src/sage/structure/parent.pyx
diff git a/src/sage/structure/parent.pyx b/src/sage/structure/parent.pyx index a387136..ea7c60c 100644
a b cdef class Parent(sage.structure.category_object.CategoryObject): 571 571 # By default, don't fiddle with extension types yet; inheritance from 572 572 # categories will probably be achieved in a different way 573 573 if inherit is None: 574 inherit = not is_extension_type(cls)574 inherit = True 575 575 if inherit: 576 576 if name is None: 577 577 name = "%s_with_category"%cls.__name__
I ran all doctests in rings
, categories
and structure
and the only nontrivial doctest failures were involving enumerated sets (src/sage/categories/examples/infinite_enumerated_sets.py
, src/sage/categories/sets_cat.py
, src/sage/categories/enumerated_sets.py
)
comment:72 Changed 6 months ago by
Hi Jeroen,
Thanks for running this interesting experiment!
I indeed would have been expecting things not too break too much. Systematically using dynamic classes would certainly simplify Sage's infrastructure. The only potential reason for not doing it is performance (speed and memory footprint). At the time we set this up, there was some consensual claim that systematically using a dynamic class would induce a performance loss for low granularity objects (e.g. finite field elements). Hence the above rule of thumb I implemented for deciding when to do what.
However I don't remember anyone doing some serious benchmarking to actually assess the validity of that claim. That would be very welcome! And this hints again at having some speedregression test infrastructure for Sage.
Cheers,
Nicolas
PS: I could imagine code breaking in situations like:
cdef class MyElement: .... cdef foo(MyElement x): x.bar()
where foo
would be called on an instance of a dynamic subclass of MyElement
, and foo
be provided by some category.
Apparently we have no instance of that idiom in Sage :)
comment:73 Changed 6 months ago by
Comments on this actual ticket: contrary to most element classes which are implemented in Cython, it seems that CombinatorialFreeModule_with_category.element_class
actually does do the inheritance from the category in the "normal" way, using dynamic_class()
, just like Python classes. So this is a good testcase for #23435.
comment:74 Changed 6 months ago by
In the light of #23435, is it important that CombinatorialFreeModule_with_category.element_class
has a __dict__
? In other words, is it important to support the following (example taken from src/doc/en/thematic_tutorials/tutorialobjectsandclasses.rst
):
Some particular actions modify the data structure of ``el``:: sage: el.rename("bla") sage: el bla .. note:: The class is stored in a particular attribute called ``__class__``, and the normal attributes are stored in a dictionary called ``__dict__``:: sage: F = CombinatorialFreeModule(QQ, Permutations()) sage: el = 3*F([1,3,2])+ F([1,2,3]) sage: el.rename("foo") sage: el.blah = 42 sage: el.__class__ <class 'sage.combinat.free_module.CombinatorialFreeModule_with_category.element_class'> sage: el.__dict__ {'__custom_name': 'foo', 'blah': 42}
comment:75 followup: ↓ 76 Changed 6 months ago by
Another question about this ticket: why are the arithmetic methods of IndexedFreeModuleElement
implemented as cdef
instead of cpdef
?
cdef _add_(self, other):
Every other class (except for IndexedFreeModuleElement
and LieAlgebraElement
) implements those as cpdef _add_
.
This is confusing because
sage: F = CombinatorialFreeModule(QQ, Permutations()) sage: el = 3*F([1,3,2])+ F([1,2,3]) sage: el._add_(el)  TypeError Traceback (most recent call last) <ipythoninput3191def7298b70> in <module>() > 1 el._add_(el) TypeError: 'NotImplementedType' object is not callable
It also prevents a Python class inheriting from IndexedFreeModuleElement
to override this _add_
.
comment:76 in reply to: ↑ 75 ; followup: ↓ 78 Changed 6 months ago by
Replying to jdemeyer:
Another question about this ticket: why are the arithmetic methods of
IndexedFreeModuleElement
implemented ascdef
instead ofcpdef
?cdef _add_(self, other):Every other class (except for
IndexedFreeModuleElement
andLieAlgebraElement
) implements those ascpdef _add_
.
That is not quite true. They are cdef
in Element
, and so I followed suit. I see now in the doc for Element
, that it says it should be cpdef
. Is it because Element
is special in that they are essentially acting as pure virtual methods that they aren't cpdef
?
comment:77 Changed 6 months ago by
Followup: #23440
comment:78 in reply to: ↑ 76 Changed 6 months ago by
Replying to tscrim:
That is not quite true. They are
cdef
inElement
, and so I followed suit. I see now in the doc forElement
, that it says it should becpdef
. Is it becauseElement
is special in that they are essentially acting as pure virtual methods that they aren'tcpdef
?
Yes, the Element
base class is special. The arithmetic methods of Element
do indeed act as "pure virtual" methods. I implemented them that way to allow fast calling in the Cython world while at the same time not existing in the Python world.
New commits:
Moving CombinatorialFreeModuleElement to own (Cython) file.