refactor: closer to current version of Protocol

Author: henryiii

setup.cfg

@@ -44,6 +44,7 @@ package_dir =
 install_requires =
     numpy >=1.13.3
     typing >= 3.5; python_version < '3.5'
+    enum34 >= 1.1; python_version < '3.4'
 
 [options.packages.find]
 where = src

src/__init__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, division, print_function
 
-from ._internal.hist import Histogram
+from ._internal.hist import Histogram, Implementation
 from . import axis, storage, accumulators, utils, numpy
 from .tag import loc, rebin, sum, underflow, overflow
 
@@ -37,6 +37,7 @@
 
 __all__ = (
     "Histogram",
+    "Implementation",
     "axis",
     "storage",
     "accumulators",

src/boost_histogram/__init__.py

@@ -0,0 +1,15 @@
+# -*- coding: utf-8 -*-
+# Try to import Enum, but if it fails, not worth breaking over.
+
+try:
+    from enum import Enum
+except ImportError:
+    try:
+        from enum34 import Enum  # type: ignore
+    except ImportError:
+        Enum = object  # type: ignore
+
+
+class Implementation(str, Enum):
+    sum = "sum"
+    mean = "mean"

src/boost_histogram/_internal/enum.py

@@ -17,6 +17,7 @@
 from .storage import Double, Storage
 from .utils import cast, register, set_family, MAIN_FAMILY, set_module
 from .view import _to_view
+from .enum import Implementation
 
 
 NOTHING = object()
@@ -789,28 +790,18 @@ def project(self, *args):
 
     # Implementation of PlottableHistogram
 
-    @property
-    def weighted(self):
-        """
-        Returns true if the storage has weight information.
-
-        :return: bool
-        """
-        view = self.view()
-        return view.dtype > 0 and hasattr(view, "variance")
-
     @property
     def implementation(self):
         """
         Returns "count" if this is a normal summing histogram, and "mean" if this is a
         mean histogram.
 
-        :return: "mean" or "count"
+        :return: Implementation
         """
         if self._storage_type in {_core.storage.mean, _core.storage.weighted_mean}:
-            return "mean"
+            return Implementation.mean
         else:
-            return "count"
+            return Implementation.sum
 
     def values(self, flow=False):
         """
@@ -840,7 +831,7 @@ def variances(self, flow=False):
 
         view = self.view(flow)
         if len(view.dtype) == 0:
-            return view
+            return None
         else:
             return view.variance
 

src/boost_histogram/_internal/hist.py

@@ -2,7 +2,7 @@ from typing import Any
 
 
 class Traits:
-    underflow
+    underflow: bool
     overflow: bool
     circular: bool
     growth: bool