sage.categories: Remove module-level imports of sage.rings, sage.algebras, sage.matrix, sage.misc.latex, etc.

[mkoeppe]

This is for a cleaner, filtered structure of our Python modules, at least regarding their load time. This is preparation for #29865 (sage-objects).

The idea is that sage.categories should be more abstract than any of the implemented algebraic structures in sage.rings, sage.algebras, sage.modules, ... Therefore it should only have a (module load time) dependence on sage.structure and sage.misc.

The present ticket changes module-level imports to method-level imports so that they are resolved later than at module load time.

At run time, of course, there are additional dependencies. For example, as noted in #29705, the output of .cardinality() must be an integer (ZZ).

Also, obviously the doctests need a larger part of the library.

(split out from #29865)

Depends on #29869
Depends on #16351

CC: @videlec @tscrim @orlitzky @nthiery @timokau @fchapoton

Component: refactoring

Author: Matthias Koeppe

Branch/Commit: 27f2dab

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/29873

[mkoeppe]

Dependencies: #29869

[mkoeppe]

Branch: u/mkoeppe/sage_categories_remove_module_level_imports

[mkoeppe]

New commits:

907feeb	Move attrcall and friends from sage.misc.misc to new module sage.misc.call
a5453bf	Fixup: Add src/sage/misc/call.py
64c5701	lazy_import from sage.misc.call with deprecation
65414f7	Fix imports and one deprecation warning
b9314d4	sage.misc.call: Add standard header information, add to reference manual
5e27414	sage.categories.crystals: Make import of sage.misc.latex local to a method
6e0fa7c	sage.categories: Make imports from sage.rings, .sets, .combinat, .plot, .matrix local to methods

[mkoeppe]

Commit: 6e0fa7c

[mkoeppe]

Description changed:

--- 
+++ 
@@ -2,9 +2,9 @@
 
 The idea is that `sage.categories` should be more abstract than any of the implemented algebraic structures in `sage.rings`, `sage.algebras`, `sage.modules`, ... Therefore it should only have a (module load time) dependence on `sage.structure` and `sage.misc`.
 
+The present ticket changes module-level imports to method-level imports so that they are resolved later than at module load time.
+
 At run time, of course, there are additional dependencies. For example, as noted in #29705, the output of `.cardinality()` must be an integer (ZZ).
-
-The present ticket changes module-level imports to method-level imports so that they are resolved later than at module load time.
 
 Also, obviously the doctests need a larger part of the library.
 

[mkoeppe]

comment:6

Branch is on top of #29869.

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:7

In this code, these extra imports at the method level will not have a meaningful effect on the run time, so I am giving this a positive review based on that. However, this is something to be aware of as there can be functions in the category framework that are used in tighter loops.

[mkoeppe]

comment:8

Thanks! Yes, let's watch out for performance impacts of some of the upcoming changes.

[mkoeppe]

comment:9

Actually now I see

  File "/local/sage-patchbot/sage/local/lib/python3.7/site-packages/sage/combinat/backtrack.py", line 76, in <module>
    from sage.sets.recursively_enumerated_set import RecursivelyEnumeratedSet_generic
  File "sage/sets/recursively_enumerated_set.pyx", line 179, in init sage.sets.recursively_enumerated_set (build/cythonized/sage/sets/recursively_enumerated_set.c:12654)
ImportError: cannot import name SearchForest

[sagetrac-git]

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

6024ffd	src/sage/misc/call.py: register_unpickle_override for call_method
f3afd30	sage.categories.crystals: Make import of sage.misc.latex local to a method
6433a56	sage.categories: Make imports from sage.rings, .sets, .combinat, .plot, .matrix local to methods

[sagetrac-git]

Changed commit from 6e0fa7c to 6433a56

[mkoeppe]

comment:11

rebased on top of newer #29869