Implement get_attribute and set_attribute

Fixes open-telemetry#239

ext/opentelemetry-ext-opentracing-shim/src/opentelemetry/ext/opentracing_shim/__init__.py

@@ -270,31 +270,13 @@ def log(self, **kwargs):
     def log_event(self, event, payload=None):
         super().log_event(event, payload=payload)
 
-    def set_baggage_item(self, key, value):  # pylint:disable=unused-argument
-        """Implements the ``set_baggage_item()`` method from the base class.
+    def set_baggage_item(self, key, value):
 
-        Warning:
-            Not implemented yet.
-        """
-
-        logger.warning(
-            "Calling unimplemented method set_baggage_item() on class %s",
-            self.__class__.__name__,
-        )
-        # TODO: Implement.
+        return self._otel_span.set_attribute(key, value)
 
-    def get_baggage_item(self, key):  # pylint:disable=unused-argument
-        """Implements the ``get_baggage_item()`` method from the base class.
+    def get_baggage_item(self, key):
 
-        Warning:
-            Not implemented yet.
-        """
-
-        logger.warning(
-            "Calling unimplemented method get_baggage_item() on class %s",
-            self.__class__.__name__,
-        )
-        # TODO: Implement.
+        return self._otel_span.get_attribute(key)
 
 
 class ScopeShim(opentracing.Scope):

opentelemetry-api/src/opentelemetry/trace/span.py

@@ -37,6 +37,13 @@ def set_attribute(self, key: str, value: types.AttributeValue) -> None:
         Sets a single Attribute with the key and value passed as arguments.
         """
 
+    @abc.abstractmethod
+    def get_attribute(self, key: str) -> types.AttributeValue:
+        """Gets an Attribute.
+
+        Gets a single Attribute with the key passed as argument.
+        """
+
     @abc.abstractmethod
     def add_event(
         self,
@@ -235,6 +242,9 @@ def end(self, end_time: typing.Optional[int] = None) -> None:
     def set_attribute(self, key: str, value: types.AttributeValue) -> None:
         pass
 
+    def get_attribute(self, key: str) -> types.AttributeValue:
+        pass
+
     def add_event(
         self,
         name: str,

opentelemetry-sdk/src/opentelemetry/sdk/trace/__init__.py

@@ -553,6 +553,10 @@ def set_attribute(self, key: str, value: types.AttributeValue) -> None:
             with self._lock:
                 self.attributes[key] = value
 
+    def get_attribute(self, key: str) -> types.AttributeValue:
+
+        return self.attributes[key]
+
     @staticmethod
     def _filter_attribute_values(attributes: types.Attributes):
         if attributes: