Add classes

Fixes open-telemetry#1835

opentelemetry-api/src/opentelemetry/metrics/__init__.py

@@ -0,0 +1,80 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+class Measurement:
+    pass
+
+
+class Instrument:
+    pass
+
+
+class Synchronous(Instrument):
+    pass
+
+
+class Asynchronous(Instrument):
+    pass
+
+
+class Adding(Instrument):
+    pass
+
+
+class Grouping(Instrument):
+    pass
+
+
+class Monotonic(Adding):
+    pass
+
+
+class NonMonotonic(Adding):
+    pass
+
+
+class Counter(Monotonic, Synchronous):
+    pass
+
+
+class UpDownCounter(NonMonotonic, Synchronous):
+    pass
+
+
+class AsynchronousCounter(Monotonic, Asynchronous):
+    pass
+
+
+class AsynchronousUpDownCounter(NonMonotonic, Asynchronous):
+    pass
+
+
+class Histogram(Synchronous, Grouping):
+    pass
+
+
+class AsynchronousGauge(Asynchronous, Grouping):
+    pass
+
+
+class Meter:
+    def create_counter(self):
+        pass
+
+
+class MeterProvider:
+
+    def provide(self, name, version=None):
+        return Meter()