[IMP] hw_drivers: Give a priority order to drivers

Previously, we tested the `supported` methods of all drivers
sequentially in alphabetical order of file names. If you wanted to
extend a driver, the `supported` method of your driver could never be
tested if the one of its parent was tested first.

We've now added a priority order to drivers so that by default the
extending driver will always be tested before the extended driver.

You can still do something similar to what `is_tested_last` did by
manually setting the priority of a driver to 0.

Ex: The way barcode scanners is really similar to keyboards, but still
requires a few modifications in the driver. We couldn't extend the
keyboard driver easily because the supported method of barcode scanners
had to be more strict than the one of keyboards. If the
KeyboardUSBDriver was tested first, scanners were recognized as
keyboard and didn't have all the specific features of scanners.

TaskID: 2082282

addons/hw_drivers/controllers/driver.py

@@ -144,7 +144,7 @@ class Interface(Thread, metaclass=InterfaceMetaClass):
 
     def __init__(self):
         super(Interface, self).__init__()
-        self.drivers = [d for d in drivers if d.connection_type == self.connection_type]
+        self.drivers = sorted([d for d in drivers if d.connection_type == self.connection_type], key=lambda d: d.priority, reverse=True)
 
     def run(self):
         while self.connection_type and self.drivers:
@@ -179,11 +179,11 @@ class Interface(Thread, metaclass=InterfaceMetaClass):
 class DriverMetaClass(type):
     def __new__(cls, clsname, bases, attrs):
         newclass = super(DriverMetaClass, cls).__new__(cls, clsname, bases, attrs)
-        # Some drivers must be tried only when all the others have been ruled out. These are kept at the bottom of the list.
-        if newclass.is_tested_last:
-            drivers.append(newclass)
+        if hasattr(newclass, 'priority'):
+            newclass.priority += 1
         else:
-            drivers.insert(0, newclass)
+            newclass.priority = 0
+        drivers.append(newclass)
         return newclass
 
 class Driver(Thread, metaclass=DriverMetaClass):
@@ -191,7 +191,6 @@ class Driver(Thread, metaclass=DriverMetaClass):
     Hook to register the driver into the drivers list
     """
     connection_type = ""
-    is_tested_last = False
 
     def __init__(self, device):
         super(Driver, self).__init__()

addons/hw_drivers/iot_handlers/drivers/SerialScaleDriver.py

@@ -247,7 +247,7 @@ class AdamEquipmentDriver(ScaleDriver):
     """Driver for the Adam Equipment serial scale."""
 
     _protocol = ADAMEquipmentProtocol
-    is_tested_last = True
+    priority = 0  # Test the supported method of this driver last, after all other serial drivers
 
     def __init__(self, device):
         super().__init__(device)