bpo-34966: Improve support of method aliases in pydoc. (GH-9823)

Pydoc now does not duplicate docstrings for aliases of inherited methods.
(cherry picked from commit a44d34e1)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Lib/pydoc.py

@@ -958,8 +958,7 @@ class HTMLDoc(Doc):
         if name == realname:
             title = '<a name="%s"><strong>%s</strong></a>' % (anchor, realname)
         else:
-            if (cl and realname in cl.__dict__ and
-                cl.__dict__[realname] is object):
+            if cl and inspect.getattr_static(cl, realname, []) is object:
                 reallink = '<a href="#%s">%s</a>' % (
                     cl.__name__ + '-' + realname, realname)
                 skipdocs = 1
@@ -1375,8 +1374,7 @@ location listed above.
         if name == realname:
             title = self.bold(realname)
         else:
-            if (cl and realname in cl.__dict__ and
-                cl.__dict__[realname] is object):
+            if cl and inspect.getattr_static(cl, realname, []) is object:
                 skipdocs = 1
             title = self.bold(name) + ' = ' + realname
         argspec = None

Lib/test/test_pydoc.py

@@ -417,6 +417,7 @@ class PydocBaseTest(unittest.TestCase):
 
 
 class PydocDocTest(unittest.TestCase):
+    maxDiff = None
 
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
@@ -648,6 +649,104 @@ class PydocDocTest(unittest.TestCase):
         methods = pydoc.allmethods(TestClass)
         self.assertDictEqual(methods, expected)
 
+    def test_method_aliases(self):
+        class A:
+            def tkraise(self, aboveThis=None):
+                """Raise this widget in the stacking order."""
+            lift = tkraise
+            def a_size(self):
+                """Return size"""
+        class B(A):
+            def itemconfigure(self, tagOrId, cnf=None, **kw):
+                """Configure resources of an item TAGORID."""
+            itemconfig = itemconfigure
+            b_size = A.a_size
+
+        doc = pydoc.render_doc(B)
+        # clean up the extra text formatting that pydoc performs
+        doc = re.sub('\b.', '', doc)
+        self.assertEqual(doc, '''\
+Python Library Documentation: class B in module %s
+
+class B(A)
+ |  Method resolution order:
+ |      B
+ |      A
+ |      builtins.object
+ |\x20\x20
+ |  Methods defined here:
+ |\x20\x20
+ |  b_size = a_size(self)
+ |\x20\x20
+ |  itemconfig = itemconfigure(self, tagOrId, cnf=None, **kw)
+ |\x20\x20
+ |  itemconfigure(self, tagOrId, cnf=None, **kw)
+ |      Configure resources of an item TAGORID.
+ |\x20\x20
+ |  ----------------------------------------------------------------------
+ |  Methods inherited from A:
+ |\x20\x20
+ |  a_size(self)
+ |      Return size
+ |\x20\x20
+ |  lift = tkraise(self, aboveThis=None)
+ |\x20\x20
+ |  tkraise(self, aboveThis=None)
+ |      Raise this widget in the stacking order.
+ |\x20\x20
+ |  ----------------------------------------------------------------------
+ |  Data descriptors inherited from A:
+ |\x20\x20
+ |  __dict__
+ |      dictionary for instance variables (if defined)
+ |\x20\x20
+ |  __weakref__
+ |      list of weak references to the object (if defined)
+''' % __name__)
+
+        doc = pydoc.render_doc(B, renderer=pydoc.HTMLDoc())
+        self.assertEqual(doc, '''\
+Python Library Documentation: class B in module %s
+
+<p>
+<table width="100%%" cellspacing=0 cellpadding=2 border=0 summary="section">
+<tr bgcolor="#ffc8d8">
+<td colspan=3 valign=bottom>&nbsp;<br>
+<font color="#000000" face="helvetica, arial"><a name="B">class <strong>B</strong></a>(A)</font></td></tr>
+\x20\x20\x20\x20
+<tr><td bgcolor="#ffc8d8"><tt>&nbsp;&nbsp;&nbsp;</tt></td><td>&nbsp;</td>
+<td width="100%%"><dl><dt>Method resolution order:</dt>
+<dd>B</dd>
+<dd>A</dd>
+<dd><a href="builtins.html#object">builtins.object</a></dd>
+</dl>
+<hr>
+Methods defined here:<br>
+<dl><dt><a name="B-b_size"><strong>b_size</strong></a> = <a href="#B-a_size">a_size</a>(self)</dt></dl>
+
+<dl><dt><a name="B-itemconfig"><strong>itemconfig</strong></a> = <a href="#B-itemconfigure">itemconfigure</a>(self, tagOrId, cnf=None, **kw)</dt></dl>
+
+<dl><dt><a name="B-itemconfigure"><strong>itemconfigure</strong></a>(self, tagOrId, cnf=None, **kw)</dt><dd><tt>Configure&nbsp;resources&nbsp;of&nbsp;an&nbsp;item&nbsp;TAGORID.</tt></dd></dl>
+
+<hr>
+Methods inherited from A:<br>
+<dl><dt><a name="B-a_size"><strong>a_size</strong></a>(self)</dt><dd><tt>Return&nbsp;size</tt></dd></dl>
+
+<dl><dt><a name="B-lift"><strong>lift</strong></a> = <a href="#B-tkraise">tkraise</a>(self, aboveThis=None)</dt></dl>
+
+<dl><dt><a name="B-tkraise"><strong>tkraise</strong></a>(self, aboveThis=None)</dt><dd><tt>Raise&nbsp;this&nbsp;widget&nbsp;in&nbsp;the&nbsp;stacking&nbsp;order.</tt></dd></dl>
+
+<hr>
+Data descriptors inherited from A:<br>
+<dl><dt><strong>__dict__</strong></dt>
+<dd><tt>dictionary&nbsp;for&nbsp;instance&nbsp;variables&nbsp;(if&nbsp;defined)</tt></dd>
+</dl>
+<dl><dt><strong>__weakref__</strong></dt>
+<dd><tt>list&nbsp;of&nbsp;weak&nbsp;references&nbsp;to&nbsp;the&nbsp;object&nbsp;(if&nbsp;defined)</tt></dd>
+</dl>
+</td></tr></table>\
+''' % __name__)
+
 
 class PydocImportTest(PydocBaseTest):
 

Misc/NEWS.d/next/Library/2018-10-12-18-57-52.bpo-34966.WZeBHO.rst

+:mod:`pydoc` now supports aliases not only to methods defined in
+the end class, but also to inherited methods.  The docstring is not
+duplicated for aliases.