Category membership, without arguments

[nthiery]

Currently one can do:

    sage: F = FreeModule(QQ,3)
    sage: F in VectorSpaces(QQ)
    True

This patch implements:

    sage: F in VectorSpaces
    True

(and does a couple closeby minor improvements to the doc)

CC: @sagetrac-sage-combinat

Component: categories

Keywords: Cernay2012

Author: Nicolas M. Thiéry

Reviewer: Florent Hivert

Merged: sage-5.0.beta6

Issue created by migration from https://trac.sagemath.org/ticket/9469

[nthiery]

Changed keywords from none to Cernay2012

[nthiery]

comment:4

Patch reviewed by Florent on the Sage-Combinat queue. Positive review on his behalf.

[nthiery]

comment:5

Florent wants to add a pointer to the feature elsewhere

[hivert]

comment:7

The new patch is Ok with me.

[nthiery]

comment:8

I just stumbled upon the following hunk later in the queue, and thought we might as well
fold it into this patch:

diff --git a/sage/categories/category.py b/sage/categories/category.py
--- a/sage/categories/category.py
+++ b/sage/categories/category.py
@@ -627,8 +627,19 @@ class Category(UniqueRepresentation, Sag
 
             sage: F in Algebras
             False
+
+        TESTS:
+
+        Non category object shall be handled properly::
+
+            sage: [1,2] in Algebras
+            False
         """
-        return any(isinstance(cat, cls) for cat in x.categories())
+        try:
+            c = x.categories()
+        except AttributeError:
+            return False
+        return any(isinstance(cat, cls) for cat in c)
 
     def is_abelian(self):
         """

I am running the tests now. Florent: shall I reinstate the positive review if the test pass?

[nthiery]

comment:10

Note: I fixed the missing 's' in 'Non category objects'.

[nthiery]

Attachment: trac_9469-category-membership_without_arguments-nt.patch.gz

[nthiery]

comment:11

I backported here your fix to the Category object link

[hivert]

comment:12

The new version is Ok with me !

[jdemeyer]

Merged: sage-5.0.beta6