Fix a couple of Characteristic bugs and add FloatCharacteristic

adafruit_ble/characteristics/__init__.py

@@ -74,7 +74,7 @@ def __bind_locally(self, service, initial_value):
         if max_length is None:
             max_length = len(initial_value)
         return _bleio.Characteristic.add_to_service(
-            service,
+            service.bleio_service,
             self.uuid.bleio_uuid,
             initial_value=initial_value,
             max_length=max_length,
@@ -138,4 +138,4 @@ def __get__(self, obj, cls=None):
 
     def __set__(self, obj, value):
         encoded = struct.pack(self._struct_format, *value)
-        super.__set__(obj, encoded)
+        super().__set__(obj, encoded)

adafruit_ble/characteristics/float.py

@@ -0,0 +1,47 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2019 Scott Shawcroft for Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+"""
+`float`
+====================================================
+
+This module provides float characteristics that are usable directly as attributes.
+
+"""
+
+from . import StructCharacteristic
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BLE.git"
+
+class FloatCharacteristic(StructCharacteristic):
+    """32-bit float"""
+    # TODO: Valid set values as within range.
+    def __init__(self, **kwargs):
+        if "initial_value" in kwargs:
+            kwargs["initial_value"] = (kwargs["initial_value"],)
+        super().__init__("<f", **kwargs)
+
+    def __get__(self, obj, cls=None):
+        return super().__get__(obj)[0]
+
+    def __set__(self, obj, value):
+        super().__set__(obj, (value,))