support slicing

tests/test_nod.py

@@ -106,11 +106,38 @@ def test_new_attr_on_existing():
 def test_addition_arithmetic():
     a = NOD(4, 2)
     b = a + a
-    assert a.as_list() == [8, 4]
+    assert b.as_list() == [8, 4]
 
 
 def test_illegal_overwrite():
     with pytest.raises(IllegalAttributeKey) as exc_info:
         NOD(update=2)
 
     assert exc_info.type is IllegalAttributeKey
+
+
+def test_slice_get():
+    a = NOD(4, 2)
+    b = a + a
+    assert b[:1] == [8]
+    assert b[-1:] == [4]
+
+
+def test_slice_get_adv():
+    a = NOD(4, 2)
+    b = a[:1] + a[0:]
+    assert b[:1] == [4]
+    assert b[-1:] == [2]
+
+
+def test_slice_set():
+    a = NOD(4, 2)
+    a[:1] = [8]
+    assert a.as_list() == [8, 2]
+
+
+def test_slice_all():
+    a = NOD(4, 2)
+    b = a + a + a
+    b[:1] = [8]
+    assert b.as_list() == [8, 6]

warg/named_ordered_dictionary.py

@@ -187,10 +187,18 @@ def __setattr__(self, key, value):
         self.__dict__[key] = value
 
     def __getitem__(self, item) -> Any:
+        if isinstance(item, slice):
+            keys = list(self.__dict__.keys())[item]
+            return [self.__dict__[a] for a in keys]
         return self.__dict__[item]
 
     def __setitem__(self, key, value):
-        self.__dict__[key] = value
+        if isinstance(key, slice):
+            keys = list(self.__dict__.keys())[key]
+            for a, v in zip(keys, value):
+                self.__dict__[a] = v
+        else:
+            self.__dict__[key] = value
 
     def keys(self):
         return self.__dict__.keys()
@@ -236,24 +244,28 @@ def update(self, *args: Any, **kwargs: Any) -> None:
         self.__dict__.update(args_dict)
 
     def __add__(self, other):
+        cop = self.__dict__.copy()
         if isinstance(other, NamedOrderedDictionary):
             for k in other.keys():
-                if k in self.__dict__:
-                    self.__dict__[k] += other.__dict__[k]
+                if k in cop:
+                    cop[k] += other.__dict__[k]
                 else:
-                    self.__dict__[k] = other.__dict__[k]
+                    cop[k] = other.__dict__[k]
         elif isinstance(other, Iterable):
             for arg in other:
                 self.add_unnamed_arg(arg)
         else:
             self.add_unnamed_arg(other)
-        return self.__dict__
+        return NOD(cop)
 
     def __sub__(self, other):
+        cop = self.__dict__.copy()
         if isinstance(other, NamedOrderedDictionary):
+
             for k in other.keys():
-                if k in self.__dict__:
-                    self.__dict__[k] -= other.__dict__[k]
+                if k in cop:
+                    cop[k] -= other.__dict__[k]
+            return NOD(cop)
         else:
             raise ArithmeticError(f"Can not subtract {type(other)} from {type(self)}")
 

warg/version.py

@@ -10,7 +10,7 @@
 from pip._internal.utils.misc import dist_is_editable
 
 __author__ = "cnheider"
-__version__ = "0.1.9"
+__version__ = "0.2.0"
 __version_info__ = tuple(int(segment) for segment in __version__.split("."))
 __doc__ = """
 Created on 27/04/2019