Fixed bad construction of class attributes in meta-class (fixes #138)

houston/ardu/common.py

@@ -53,6 +53,7 @@ class ArmDisarm(Command):
         Idle: if the conditions above cannot be met, the robot will ignore the
             command.
     """
+    uid = 'ardu:common:arm'
     name = 'arm'
     parameters = [
         Parameter('arm', DiscreteValueRange([True, False]))

houston/command.py

@@ -81,6 +81,28 @@ def __new__(mcl,
             raise TypeError(tpl_err.format(msg))
         logger.debug("obtained command name: %s", name_command)
 
+        # obtain UID
+        logger.debug("obtaining command UID")
+        if 'uid' not in ns:
+            msg = "missing 'uid' field in Command definition"
+            raise TypeError(tpl_err.format(msg))
+
+        uid = ns['uid']
+        if not isinstance(uid, str):
+            t = type(uid)
+            msg = "expected 'uid' field to be str but was {}".format(t)
+            raise TypeError(tpl_err.format(msg))
+        logger.debug("using provided UID: %s", uid)
+
+        # ensure uid is not an empty string
+        if uid == '':
+            msg = "'uid' field must not be an empty string"
+            raise TypeError(tpl_err.format(msg))
+
+        # FIXME convert uid to a read-only attribute
+
+        logger.debug("obtained command UID: %s", uid)
+
         # ensure "to_message" is implemented
         if 'to_message' not in ns:
             msg = "missing 'to_message' method in Command definition"
@@ -142,26 +164,8 @@ def __init__(cls, cls_name: str, bases, ns: Dict[str, Any]):
         tpl_err = "failed to build definition for command [{}]: "
         tpl_err = tpl_err.format(cls_name) + "{}"
 
-        # obtain or generate a unique identifier
-        if 'uid' in ns:
-            uid = ns['uid']
-            if not isinstance(uid, str):
-                t = type(uid)
-                msg = "expected 'uid' field to be str but was {}".format(t)
-                raise TypeError(tpl_err.format(msg))
-            logger.debug("using provided UID: %s", uid)
-        else:
-            uid = '{}.{}'.format(cls.__module__, cls.__qualname__)
-
-        # ensure uid is not an empty string
-        if uid == '':
-            msg = "'uid' field must not be an empty string"
-            raise TypeError(tpl_err.format(msg))
-
-        # convert uid to a read-only property
-        ns['uid'] = property(lambda u=uid: u)
-
         # ensure that uid isn't already in use
+        uid = ns['uid']  # type: str
         if uid in _UID_TO_COMMAND_TYPE:
             msg = "'uid' already in use [%s]".format(uid)
             raise TypeError(tpl_error.format(msg))

houston/system.py

@@ -37,8 +37,8 @@ def __new__(mcl,
         else:
             is_abstract = False
 
-        # construct an immutable "is_abstract" property
-        ns['is_abstract'] = property(lambda self, v=is_abstract: v)
+        # FIXME create immutable attribute
+        ns['is_abstract'] = is_abstract
 
         if not is_abstract:
             if 'name' not in ns:
@@ -52,7 +52,9 @@ def __new__(mcl,
             if sys_name == '':
                 msg = "System name must be a non-empty string."
                 raise TypeError(msg)
-            ns['name'] = property(lambda self, n=sys_name: n)
+
+            # FIXME create immutable class attribute
+            ns['name'] = sys_name
 
             if 'state' not in ns:
                 msg = "System class definition is missing 'state' property"

test/test_command.py

@@ -14,6 +14,7 @@ class M1(Message):
         foo = attr.ib(type=str)
 
     class C1(Command):
+        uid = 'test:c1'
         name = 'c1'
         parameters = [
             Parameter('foo', DiscreteValueRange(['ON', 'OFF']))

test/test_properties.py

@@ -0,0 +1,14 @@
+import pytest
+
+from houston.ardu.common import ArmDisarm
+from houston.ardu.copter.goto import GoTo as CopterGoTo
+from houston.ardu.copter import ArduCopter
+
+
+def test_command_uid():
+    assert CopterGoTo.uid == 'ardu:copter:goto'
+    assert ArmDisarm.uid == 'ardu:common:arm'
+
+
+def test_system_name():
+    assert ArduCopter.name == 'arducopter'