From 3a0a9f659e436f1f38d12a784cb01379e20f139f Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Sat, 16 Feb 2019 23:40:45 +0900
Subject: [PATCH] refactor: import_object() allows to import nested objects
 (ex. nested class)

---
 sphinx/util/__init__.py | 34 +++++++++++++++++++---------------
 tests/test_util.py      | 24 ++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 17 deletions(-)

diff --git a/sphinx/util/__init__.py b/sphinx/util/__init__.py
index bfe99778a..9c78630ff 100644
--- a/sphinx/util/__init__.py
+++ b/sphinx/util/__init__.py
@@ -603,22 +603,26 @@ class PeekableIterator:
 
 def import_object(objname, source=None):
     # type: (str, str) -> Any
+    """Import python object by qualname."""
     try:
-        module, name = objname.rsplit('.', 1)
-    except ValueError as err:
-        raise ExtensionError('Invalid full object name %s' % objname +
-                             (source and ' (needed for %s)' % source or ''),
-                             err)
-    try:
-        return getattr(__import__(module, None, None, [name]), name)
-    except ImportError as err:
-        raise ExtensionError('Could not import %s' % module +
-                             (source and ' (needed for %s)' % source or ''),
-                             err)
-    except AttributeError as err:
-        raise ExtensionError('Could not find %s' % objname +
-                             (source and ' (needed for %s)' % source or ''),
-                             err)
+        objpath = objname.split('.')
+        modname = objpath.pop(0)
+        obj = __import__(modname)
+        for name in objpath:
+            modname += '.' + name
+            try:
+                obj = getattr(obj, name)
+            except AttributeError:
+                __import__(modname)
+                obj = getattr(obj, name)
+
+        return obj
+    except (AttributeError, ImportError) as exc:
+        if source:
+            raise ExtensionError('Could not import %s (needed for %s)' %
+                                 (objname, source), exc)
+        else:
+            raise ExtensionError('Could not import %s' % objname, exc)
 
 
 def encode_uri(uri):
diff --git a/tests/test_util.py b/tests/test_util.py
index 0926096f4..bcac4b654 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -15,11 +15,11 @@ import pytest
 from mock import patch
 
 import sphinx
-from sphinx.errors import PycodeError
+from sphinx.errors import ExtensionError, PycodeError
 from sphinx.testing.util import strip_escseq
 from sphinx.util import (
     SkipProgressMessage, display_chunk, encode_uri, ensuredir, get_module_source,
-    parselinenos, progress_message, status_iterator, xmlname_checker
+    import_object, parselinenos, progress_message, status_iterator, xmlname_checker
 )
 from sphinx.util import logging
 
@@ -71,6 +71,26 @@ def test_get_module_source():
         get_module_source('itertools')
 
 
+def test_import_object():
+    module = import_object('sphinx')
+    assert module.__name__ == 'sphinx'
+
+    module = import_object('sphinx.application')
+    assert module.__name__ == 'sphinx.application'
+
+    obj = import_object('sphinx.application.Sphinx')
+    assert obj.__name__ == 'Sphinx'
+
+    with pytest.raises(ExtensionError) as exc:
+        import_object('sphinx.unknown_module')
+    assert exc.value.args[0] == 'Could not import sphinx.unknown_module'
+
+    with pytest.raises(ExtensionError) as exc:
+        import_object('sphinx.unknown_module', 'my extension')
+    assert exc.value.args[0] == ('Could not import sphinx.unknown_module '
+                                 '(needed for my extension)')
+
+
 @pytest.mark.sphinx('dummy')
 @patch('sphinx.util.console._tw', 40)  # terminal width = 40
 def test_status_iterator(app, status, warning):