Trac #34211: Fix bug due to a call to SSLContext() in src/sage/graphs…

…/isgci.py

{{{
sage: graph_classes._download_db()
------------------------------------------------------------------------
---
NameError                                 Traceback (most recent call
last)
<ipython-input-1-3914f28ce325> in <module>
----> 1 graph_classes._download_db()

/home/dcoudert/sage/local/var/lib/sage/venv-python3.10/lib64/python3.10
/site-packages/sage/graphs/isgci.py in _download_db(self)
    829         import tempfile
    830         u = urlopen('https://www.graphclasses.org/data.zip',
--> 831                     context=SSLContext())
    832         with tempfile.NamedTemporaryFile(suffix=".zip") as f:
    833             f.write(u.read())

NameError: name 'SSLContext' is not defined
}}}

This bug was fixed in #33771, replacing the call to `SSLContext()` in
`src/sage/graphs/isgci.py` with a call to `default_context()`, but this
changes has been reverted in #33829.

----
Dependency on #34079 since it modifies this file.

URL: https://trac.sagemath.org/34211
Reported by: dcoudert
Ticket author(s): David Coudert
Reviewer(s): Dima Pasechnik

build/pkgs/configure/checksums.ini

@@ -1,4 +1,4 @@
 tarball=configure-VERSION.tar.gz
-sha1=901e5c9e8a79b5c68df39b889e8b4698fd230faa
-md5=91edef000fa263a8614786c634487b02
-cksum=208681990
+sha1=5e524f1afff2888475c49f1652efc292b3a4c7b6
+md5=c3859fac3716ac64800f176c54389089
+cksum=3271526260

build/pkgs/configure/package-version.txt

@@ -1 +1 @@
-461a23c8a43375d7902f3723c313729b2effd62d
+02cbc86624701318edfee6cd1c2f59c226f4a588

src/sage/graphs/isgci.py

@@ -55,30 +55,13 @@
     -------------------------
     id                             :  gc_32
     name                           :  chordal
-    type                           :  base
-    <BLANKLINE>
+    ...
     Problems :
     -----------
     3-Colourability                :  Linear
     Clique                         :  Polynomial
     Clique cover                   :  Polynomial
-    Cliquewidth                    :  Unbounded
-    Cliquewidth expression         :  NP-complete
-    Colourability                  :  Linear
-    Cutwidth                       :  NP-complete
-    Domination                     :  NP-complete
-    Feedback vertex set            :  Polynomial
-    Hamiltonian cycle              :  NP-complete
-    Hamiltonian path               :  NP-complete
-    Independent set                :  Linear
-    Maximum bisection              :  Unknown
-    Maximum cut                    :  NP-complete
-    Minimum bisection              :  Unknown
-    Recognition                    :  Linear
-    Treewidth                      :  Polynomial
-    Weighted clique                :  Polynomial
-    Weighted feedback vertex set   :  Unknown
-    Weighted independent set       :  Linear
+    ...
 
 It is possible to obtain the complete list of the classes stored in ISGCI by
 calling the :meth:`~GraphClasses.show_all` method (beware -- long output)::
@@ -637,30 +620,15 @@ def description(self):
             -------------------------
             id                             :  gc_32
             name                           :  chordal
-            type                           :  base
-            <BLANKLINE>
+            ...
             Problems :
             -----------
             3-Colourability                :  Linear
             Clique                         :  Polynomial
             Clique cover                   :  Polynomial
-            Cliquewidth                    :  Unbounded
-            Cliquewidth expression         :  NP-complete
-            Colourability                  :  Linear
-            Cutwidth                       :  NP-complete
-            Domination                     :  NP-complete
-            Feedback vertex set            :  Polynomial
-            Hamiltonian cycle              :  NP-complete
-            Hamiltonian path               :  NP-complete
-            Independent set                :  Linear
-            Maximum bisection              :  Unknown
-            Maximum cut                    :  NP-complete
-            Minimum bisection              :  Unknown
+            ...
             Recognition                    :  Linear
-            Treewidth                      :  Polynomial
-            Weighted clique                :  Polynomial
-            Weighted feedback vertex set   :  Unknown
-            Weighted independent set       :  Linear
+            ...
         """
         classes = GraphClasses().classes()
         cls = classes[self._gc_id]
@@ -737,7 +705,7 @@ def classes(self):
             sage: type(t)
             <... 'dict'>
             sage: sorted(t["gc_151"].keys())
-            ['id', 'name', 'problem', 'type']
+            ['id', 'name',... 'problem',... 'type']
             sage: t["gc_151"]['name']
             'cograph'
             sage: t["gc_151"]['problem']['Clique']
@@ -780,16 +748,14 @@ def smallgraphs(self):
         EXAMPLES::
 
             sage: t = graph_classes.smallgraphs()
-            sage: t
-            {'2C_4': Graph on 8 vertices,
-             '2K_2': Graph on 4 vertices,
-             '2K_3': Graph on 6 vertices,
-             '2K_3 + e': Graph on 6 vertices,
-             '2K_4': Graph on 8 vertices,
-             '2P_3': Graph on 6 vertices,
-            ...
+            sage: t['2C_4']
+            Graph on 8 vertices
+            sage: t['2K_3 + e']
+            Graph on 6 vertices
             sage: t['fish']
             Graph on 6 vertices
+            sage: t['bull']
+            Graph on 5 vertices
         """
         self._get_ISGCI()
         return self.smallgraphs()
@@ -827,11 +793,11 @@ def _download_db(self):
 
         EXAMPLES::
 
-            sage: graph_classes._download_db() # Not tested -- requires internet
+            sage: graph_classes._download_db()  # optional - internet
         """
         import tempfile
         u = urlopen('https://www.graphclasses.org/data.zip',
-                    context=SSLContext())
+                    context=default_context())
         with tempfile.NamedTemporaryFile(suffix=".zip") as f:
             f.write(u.read())
             z = zipfile.ZipFile(f.name)
@@ -858,7 +824,6 @@ def _parse_db(self, directory):
             sage: graph_classes._parse_db(GRAPHS_DATA_DIR)
         """
         import xml.etree.cElementTree as ET
-        import os.path
         from sage.graphs.graph import Graph
 
         xml_file = os.path.join(GRAPHS_DATA_DIR, _XML_FILE)
@@ -903,7 +868,7 @@ def update_db(self):
 
         EXAMPLES::
 
-            sage: graph_classes.update_db() # Not tested -- requires internet
+            sage: graph_classes.update_db()  # optional - internet
         """
         self._download_db()
 
@@ -935,8 +900,6 @@ def _get_ISGCI(self):
 
             sage: graph_classes._get_ISGCI()  # long time (4s on sage.math, 2012)
         """
-
-        import os.path
         from sage.misc.misc import SAGE_DB
 
         try:
@@ -1039,12 +1002,11 @@ def _XML_to_dict(root):
 
     EXAMPLES::
 
-        sage: graph_classes.Perfect.description() # indirect doctest
+        sage: graph_classes.Perfect.description()  # indirect doctest
         Class of graphs : Perfect
         -------------------------
         id                             :  gc_56
         name                           :  perfect
-        type                           :  base
         ...
     """
     ans = root.attrib.copy()