Add ABCs CommutativePolynomial, MPolynomial_libsingular, InfinitePolynomial; deprecate is_Polynomial, is_MPolynomial

[mkoeppe]

isinstance(x, [M]Polynomial) replaces the use of is_Polynomial, is_MPolynomial (deprecated here).

The new class CommutativePolynomial is an ABC that is a common base of Polynomial, MPolynomial, and InfinitePolynomial. We introduce it here although there is currently no use for isinstance(x, CommutativePolynomial) in the library.

The new class InfinitePolynomial is a common base class of InfinitePolynomial_sparse and InfinitePolynomial_dense. Methods shared between both classes are moved to the new class.

The new class MPolynomial_libsingular is an ABCDEFIT (ABC defined exclusively for isinstance tests) with a unique direct subclass (see Meta-ticket #32414 and https://doc.sagemath.org/html/en/developer/packaging_sage_library.html#module-level-runtime-dependencies for this design pattern). Its purpose is to replace uses of isinstance(x, MPolynomial_libsingular) throughout the library. This eliminates hard run-time dependencies on Singular.

We also make sage.rings.polynomial a namespace package; this is needed because element implementations depend on various libraries.

CC: @dimpase @mezzarobba @videlec @tscrim

Component: refactoring

Author: Matthias Koeppe

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/32709

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Branch: u/mkoeppe/sage_structure_element__add_abcs_polynomial__mpolynomial_for_isinstance_testing

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

4185472

Fixups

[sagetrac-git]

Commit: 4185472

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,4 +1,4 @@
-... replacing the use of `is_Polynomial`, `is_MPolynomial`.
+... replacing the use of `is_Polynomial`, `is_MPolynomial` (deprecated here).
 
 Part of Meta-ticket #32414
 

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

46d8351

sage.rings.polynomial: Make it a namespace package

[sagetrac-git]

Changed commit from 4185472 to 46d8351

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,4 +1,6 @@
 ... replacing the use of `is_Polynomial`, `is_MPolynomial` (deprecated here).
+
+We also make `sage.rings.polynomial` a namespace package; this is needed because element implementations depend on various libraries.
 
 Part of Meta-ticket #32414
 

[sagetrac-git]

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

29d91ad	sage.structure.element: Add ABCs Polynomial, MPolynomial, use for isinstance testing
ed9e0e4	Use ABC MPolynomial for isinstance testing
f4b0aa7	Fixups
e21267f	sage.rings.polynomial: Make it a namespace package

[sagetrac-git]

Changed commit from 46d8351 to e21267f

[tscrim]

comment:14

Merge failure.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

e156cad

Merge tag '9.8.beta6' into t/32709/sage_structure_element__add_abcs_polynomial__mpolynomial_for_isinstance_testing

[sagetrac-git]

Changed commit from e21267f to e156cad