fix #233 fix #231 reverting to subclass dict resp list for CommentedMap/Seq0.15.70

had to reimplement round-trippable mappings with merge-keys to get both JSON dumping and
casting using dict(**some_commented_map) to work.

(JSON dump of merge maps not tested)

*When this change indeed resolves your problem, please **Close** this issue*.
*(You can do so using the WorkFlow pull-down (close to the top right of this page))*

6 files changed, 61 insertions, 36 deletions

diff --git a/CHANGES b/CHANGES
index 6b8208e..2b64da8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,11 @@
+[0, 15, 70]: 2018-09-21
+  - reverted CommentedMap and CommentedSeq to subclass ordereddict resp. list,
+    reimplemented merge maps so that both ``dict(**commented_map_instance)`` and JSON
+    dumping works. This also allows checking with ``isinstance()`` on ``dict`` resp. ``list``.
+    (Proposed by `Stuart Berg <https://bitbucket.org/stuarteberg/>`__, with feedback
+    from `blhsing <https://stackoverflow.com/users/6890912/blhsing>`__ on
+    `StackOverflow <https://stackoverflow.com/q/52314186/1307905>`__)
+
 [0, 15, 69]: 2018-09-20
   - fix issue with dump_all gobbling end-of-document comments on parsing
     (reported by `Pierre B. <https://bitbucket.org/octplane/>`__)
diff --git a/README.rst b/README.rst
index 607fd5e..04f6783 100644
--- a/README.rst
+++ b/README.rst
@@ -4,8 +4,8 @@ ruamel.yaml
 
 ``ruamel.yaml`` is a YAML 1.2 loader/dumper package for Python.
 
-:version:       0.15.69
-:updated:       2018-09-20
+:version:       0.15.70
+:updated:       2018-09-21
 :documentation: http://yaml.readthedocs.io
 :repository:    https://bitbucket.org/ruamel/
 :pypi:          https://pypi.org/project/ruamel.yaml/
@@ -54,6 +54,14 @@ ChangeLog
 
 .. should insert NEXT: at the beginning of line for next key (with empty line)
 
+0.15.70 (2018-09-21):
+  - reverted CommentedMap and CommentedSeq to subclass ordereddict resp. list,
+    reimplemented merge maps so that both ``dict(**commented_map_instance)`` and JSON
+    dumping works. This also allows checking with ``isinstance()`` on ``dict`` resp. ``list``.
+    (Proposed by `Stuart Berg <https://bitbucket.org/stuarteberg/>`__, with feedback
+    from `blhsing <https://stackoverflow.com/users/6890912/blhsing>`__ on
+    `StackOverflow <https://stackoverflow.com/q/52314186/1307905>`__)
+
 0.15.69 (2018-09-20):
   - fix issue with dump_all gobbling end-of-document comments on parsing
     (reported by `Pierre B. <https://bitbucket.org/octplane/>`__)
diff --git a/__init__.py b/__init__.py
index 16bfa0c..6ffb2d4 100644
--- a/__init__.py
+++ b/__init__.py
@@ -7,8 +7,8 @@ if False:  # MYPY
 
 _package_data = dict(
     full_package_name='ruamel.yaml',
-    version_info=(0, 15, 69),
-    __version__='0.15.69',
+    version_info=(0, 15, 70),
+    __version__='0.15.70',
     author='Anthon van der Neut',
     author_email='a.van.der.neut@ruamel.eu',
     description='ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order',  # NOQA
diff --git a/_doc/_static/pypi.svg b/_doc/_static/pypi.svg
index c73ced3..8b244c0 100644
--- a/_doc/_static/pypi.svg
+++ b/_doc/_static/pypi.svg
@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.69</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.69</text></g> </svg>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="86" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="a"><rect width="86" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#a)"><path fill="#555" d="M0 0h33v20H0z"/><path fill="#007ec6" d="M33 0h53v20H33z"/><path fill="url(#b)" d="M0 0h86v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="110"> <text x="175" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="230">pypi</text><text x="175" y="140" transform="scale(.1)" textLength="230">pypi</text><text x="585" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="430">0.15.70</text><text x="585" y="140" transform="scale(.1)" textLength="430">0.15.70</text></g> </svg>
diff --git a/_test/test_issues.py b/_test/test_issues.py
index 2651cff..80be4f4 100644
--- a/_test/test_issues.py
+++ b/_test/test_issues.py
@@ -187,13 +187,12 @@ class TestIssues:
         assert res == yaml_str.replace(' b ', ' B ').replace(' d\n', ' D\n')
 
     def test_issue_176_test_slicing(self):
-        from ruamel.yaml.comments import CommentedSeq
+        from ruamel.yaml.compat import PY2
 
         mss = round_trip_load('[0, 1, 2, 3, 4]')
         assert len(mss) == 5
         assert mss[2:2] == []
         assert mss[2:4] == [2, 3]
-        assert isinstance(mss[2:4], CommentedSeq)
         assert mss[1::2] == [1, 3]
 
         # slice assignment
@@ -219,10 +218,18 @@ class TestIssues:
         m[1::2] = [42, 43]
         assert m == [0, 42, 2, 43, 4]
         m = mss[:]
-        with pytest.raises(TypeError, match='too many'):
-            m[1::2] = [42, 43, 44]
-        with pytest.raises(TypeError, match='not enough'):
-            m[1::2] = [42]
+        if PY2:
+            with pytest.raises(ValueError, match='attempt to assign'):
+                m[1::2] = [42, 43, 44]
+        else:
+            with pytest.raises(TypeError, match='too many'):
+                m[1::2] = [42, 43, 44]
+        if PY2:
+            with pytest.raises(ValueError, match='attempt to assign'):
+                m[1::2] = [42]
+        else:
+            with pytest.raises(TypeError, match='not enough'):
+                m[1::2] = [42]
         m = mss[:]
         m += [5]
         m[1::2] = [42, 43, 44]
@@ -408,7 +415,6 @@ class TestIssues:
         with pytest.raises(ruamel.yaml.parser.ParserError):
             yaml.safe_load('{]')
 
-    # @pytest.mark.xfail(strict=True, reason='not a dict subclass', raises=TypeError)
     def test_issue_233(self):
         from ruamel.yaml import YAML
         import json
@@ -417,7 +423,6 @@ class TestIssues:
         data = yaml.load('{}')
         json_str = json.dumps(data)  # NOQA
 
-    @pytest.mark.xfail(strict=True, reason='not a list subclass', raises=TypeError)
     def test_issue_233a(self):
         from ruamel.yaml import YAML
         import json
diff --git a/comments.py b/comments.py
index 9730f0a..b54f45a 100644
--- a/comments.py
+++ b/comments.py
@@ -385,16 +385,16 @@ class CommentedBase(object):
         raise NotImplementedError
 
 
-class CommentedSeq(MutableSliceableSequence, CommentedBase):
+class CommentedSeq(MutableSliceableSequence, list, CommentedBase):
     __slots__ = (Comment.attrib, '_lst')
 
     def __init__(self, *args, **kw):
         # type: (Any, Any) -> None
-        self._lst = list(*args, **kw)
+        list.__init__(self, *args, **kw)
 
     def __getsingleitem__(self, idx):
         # type: (Any) -> Any
-        return self._lst[idx]
+        return list.__getitem__(self, idx)
 
     def __setsingleitem__(self, idx, value):
         # type: (Any, Any) -> None
@@ -406,11 +406,11 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
                 and isinstance(self[idx], ScalarString)
             ):
                 value = type(self[idx])(value)
-        self._lst.__setitem__(idx, value)
+        list.__setitem__(self, idx, value)
 
     def __delsingleitem__(self, idx=None):
         # type: (Any) -> Any
-        del self._lst[idx]
+        list.__delitem__(self, idx)
         self.ca.items.pop(idx, None)  # might not be there -> default value
         for list_index in sorted(self.ca.items):
             if list_index < idx:
@@ -419,12 +419,12 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
 
     def __len__(self):
         # type: () -> int
-        return len(self._lst)
+        return list.__len__(self)
 
     def insert(self, idx, val):
         # type: (Any, Any) -> None
         """the comments after the insertion have to move forward"""
-        self._lst.insert(idx, val)
+        list.insert(self, idx, val)
         for list_index in sorted(self.ca.items, reverse=True):
             if list_index < idx:
                 break
@@ -432,11 +432,11 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
 
     def extend(self, val):
         # type: (Any) -> None
-        self._lst.extend(val)
+        list.extend(self, val)
 
     def __eq__(self, other):
         # type: (Any) -> bool
-        return bool(self._lst == other)
+        return list.__eq__(self, other)
 
     def _yaml_add_comment(self, comment, key=NoComment):
         # type: (Any, Optional[Any]) -> None
@@ -494,16 +494,18 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
 
     def __add__(self, other):
         # type: (Any) -> Any
-        return self._lst + other
+        return list.__add__(self, other)
 
-    def sort(self, key=None, reverse=False):
+    def sort(self, key=None, reverse=False):  # type: ignore
         # type: (Any, bool) -> None
         if key is None:
-            tmp_lst = sorted(zip(self._lst, range(len(self._lst))), reverse=reverse)
-            self._lst = [x[0] for x in tmp_lst]
+            tmp_lst = sorted(zip(self, range(len(self))), reverse=reverse)
+            list.__init__(self, [x[0] for x in tmp_lst])
         else:
-            tmp_lst = sorted(zip(map(key, self._lst), range(len(self._lst))), reverse=reverse)
-            self._lst = [self._lst[x[1]] for x in tmp_lst]
+            tmp_lst = sorted(
+                zip(map(key, list.__iter__(self)), range(len(self))), reverse=reverse
+            )
+            list.__init__(self, [list.__getitem__(self, x[1]) for x in tmp_lst])
         itm = self.ca.items
         self.ca._items = {}
         for idx, x in enumerate(tmp_lst):
@@ -513,7 +515,7 @@ class CommentedSeq(MutableSliceableSequence, CommentedBase):
 
     def __repr__(self):
         # type: () -> Any
-        return self._lst.__repr__()
+        return list.__repr__(self)
 
 
 class CommentedKeySeq(tuple, CommentedBase):
@@ -638,13 +640,13 @@ class CommentedMapValuesView(CommentedMapView):
 
 
 class CommentedMap(MutableMapping, ordereddict, CommentedBase):
-    __slots__ = (Comment.attrib, '_ok', '_ref')  # own keys
+    __slots__ = (Comment.attrib, '_ok', '_ref')
 
     def __init__(self, *args, **kw):
         # type: (Any, Any) -> None
-        ordereddict.__init__(self, *args, **kw)
-        self._ok = set()
-        self._ref = []
+        ordereddict.__init__(self, *args, **kw)  # type: ignore
+        self._ok = set()  # type: MutableSet[Any]  #  own keys
+        self._ref = []  # type: List[CommentedMap]
 
     def _yaml_add_comment(self, comment, key=NoComment, value=NoComment):
         # type: (Any, Optional[Any], Optional[Any]) -> None
@@ -707,7 +709,7 @@ class CommentedMap(MutableMapping, ordereddict, CommentedBase):
         # type: (Any) -> None
         try:
             ordereddict.update(self, vals)
-            self._ok.update(vals.keys())
+            self._ok.update(vals.keys())  # type: ignore
         except TypeError:
             # probably a dict that is used
             for x in vals:
@@ -780,7 +782,7 @@ class CommentedMap(MutableMapping, ordereddict, CommentedBase):
 
     def __contains__(self, key):
         # type: (Any) -> bool
-        return ordereddict.__contains__(self, key)
+        return bool(ordereddict.__contains__(self, key))
 
     def get(self, key, default=None):
         # type: (Any, Any) -> Any
@@ -831,7 +833,7 @@ class CommentedMap(MutableMapping, ordereddict, CommentedBase):
 
     def __len__(self):
         # type: () -> int
-        return ordereddict.__len__(self)
+        return ordereddict.__len__(self)  # type: ignore
 
     def __eq__(self, other):
         # type: (Any) -> bool
@@ -922,6 +924,7 @@ class CommentedMap(MutableMapping, ordereddict, CommentedBase):
         return x
 
     def add_referent(self, cm):
+        # type: (Any) -> None
         if cm not in self._ref:
             self._ref.append(cm)
 
@@ -936,6 +939,7 @@ class CommentedMap(MutableMapping, ordereddict, CommentedBase):
         self.merge.extend(value)
 
     def update_key_value(self, key):
+        # type: (Any) -> None
         if key in self._ok:
             return
         for v in self.merge: