signals: Support extending of Inputs/Outputs classes

Orange/widgets/model/owlinearregression.py

@@ -25,8 +25,8 @@ class OWLinearRegression(OWBaseLearner):
 
     LEARNER = LinearRegressionLearner
 
-    class Outputs:
-        coefficients = Output("Coefficients", Table, explicit=True)
+    class Outputs(OWBaseLearner.Outputs):
+        coefficients = Output("Coefficients", Table)
 
     #: Types
     REGULARIZATION_TYPES = ["No regularization", "Ridge regression (L2)",

Orange/widgets/model/owlogisticregression.py

@@ -7,7 +7,7 @@
 from Orange.classification.logistic_regression import LogisticRegressionLearner
 from Orange.widgets import settings, gui
 from Orange.widgets.utils.owlearnerwidget import OWBaseLearner
-from Orange.widgets.widget import Output
+from Orange.widgets.utils.signals import Output
 
 
 class OWLogisticRegression(OWBaseLearner):
@@ -22,8 +22,8 @@ class OWLogisticRegression(OWBaseLearner):
 
     LEARNER = LogisticRegressionLearner
 
-    class Outputs:
-        coefficients = Output("Coefficients", Table, explicit=True)
+    class Outputs(OWBaseLearner.Outputs):
+        coefficients = Output("Coefficients", Table)
 
     penalty_type = settings.Setting(1)
     C_index = settings.Setting(61)

Orange/widgets/utils/signals.py

@@ -1,4 +1,5 @@
 import copy
+import inspect
 import itertools
 
 from Orange.canvas.registry.description import InputSignal, OutputSignal
@@ -145,6 +146,12 @@ def send(self, value, id=None):
             signal_manager.send(self.widget, self.name, value, id)
 
 
+def _get_members(obj, member_type):
+    def is_member_type(member):
+        return isinstance(member, member_type)
+    return inspect.getmembers(obj, is_member_type)
+
+
 class WidgetSignalsMixin:
     """Mixin for managing widget's input and output signals"""
     class Inputs:
@@ -158,9 +165,8 @@ def __init__(self):
 
     def _bind_outputs(self):
         bound_cls = self.Outputs()
-        for name, signal in self.Outputs.__dict__.items():
-            if isinstance(signal, Output):
-                bound_cls.__dict__[name] = signal.bound_signal(self)
+        for name, signal in _get_members(bound_cls, Output):
+            setattr(bound_cls, name, signal.bound_signal(self))
         setattr(self, "Outputs", bound_cls)
 
     def send(self, signalName, value, id=None):
@@ -210,8 +216,9 @@ def signal_from_args(args, signal_type):
 
     @classmethod
     def _check_input_handlers(cls):
-        unbound = [signal.name for signal in cls.Inputs.__dict__.values()
-                   if isinstance(signal, Input) and not signal.handler]
+        unbound = [signal.name
+                   for _, signal in _get_members(cls.Inputs, Input)
+                   if not signal.handler]
         if unbound:
             raise ValueError("unbound signal(s) in {}: {}".
                              format(cls.__name__, ", ".join(unbound)))
@@ -242,8 +249,7 @@ def get_signals(cls, direction):
             return old_style
 
         signal_class = getattr(cls, direction.title())
-        signals = [signal for signal in signal_class.__dict__.values()
-                   if isinstance(signal, _Signal)]
+        signals = [signal for _, signal in _get_members(signal_class, _Signal)]
         return list(sorted(signals, key=lambda s: s._seq_id))