OWPythonScript: Avoid meta class

Orange/canvas/scheme/widgetsscheme.py

@@ -16,6 +16,7 @@
   :bases:
 
 """
+import inspect
 import sys
 import logging
 import traceback
@@ -819,7 +820,10 @@ def process_signals_for_widget(self, node, widget, signals):
 
             app.setOverrideCursor(Qt.WaitCursor)
             try:
-                handler(*args)
+                if "signal" in inspect.signature(handler).parameters:
+                    handler(*args, signal=link.sink_channel)
+                else:
+                    handler(*args)
             except Exception:
                 sys.excepthook(*sys.exc_info())
                 log.exception("Error calling '%s' of '%s'",

Orange/widgets/data/owpythonscript.py

@@ -1,3 +1,4 @@
+import inspect
 import sys
 import os
 import code
@@ -351,57 +352,50 @@ def select_row(view, row):
                     QItemSelectionModel.ClearAndSelect)
 
 
-class OWPythonScriptMeta(type(widget.OWWidget)):
-    inputs = (("data", Table), ("learner", Learner), ("classifier", Model),
-              ("object", object))
-    outputs = inputs
-
-    # pylint: disable=no-self-argument
-    def __prepare__(cls_name, bases, **kwargs):
-        inputs = OWPythonScriptMeta.inputs
-        outputs = OWPythonScriptMeta.outputs
-
-        inputs_cls = type(
-            "Inputs", (object, ),
-            {"in_" + name: Input("in_" + name, type_,
-                                 default=type_ is not object, multiple=True)
-             for name, type_ in inputs})
-
-        outputs_cls = type(
-            "Outputs", (object,),
-            {"out_" + name: Output("out_" + name, type_)
-             for name, type_ in outputs})
-
-        namespace = {"Inputs": inputs_cls,
-                     "input_names": ["in_" + name for name, _ in inputs],
-                     "Outputs": outputs_cls,
-                     "output_names": ["out_" + name for name, _ in outputs]}
-
-        for name, _ in inputs:
-            # `name` is needed to circumvent Python closure bug
-            def handler(self, obj, id=None, name=name):
-                id = id[0]
-                dic = getattr(self, "in_" + name)
-                if obj is None:
-                    if id in dic.keys():
-                        del dic[id]
-                else:
-                    dic[id] = obj
-            handler.__name__ = "set_" + name
-            decorator = getattr(inputs_cls, "in_" + name)
-            namespace.setdefault("set_" + name, decorator(handler))
-        return namespace
+def _create_signals(handler, inputs, outputs):
+    class Inputs:
+        pass
+
+    class Outputs:
+        pass
+
+    for name, type_ in inputs:
+        inp = Input("in_" + name, type_,
+                    default=type_ is not object, multiple=True)
+        setattr(Inputs, "in_" + name, inp)
+        inp(handler)
+
+    for name, type_ in outputs:
+        out = Output("out_" + name, type_)
+        setattr(Outputs, "out_" + name, out)
 
+    return Inputs, Outputs
 
-# I've no idea why pylint gives warning about this meta class
-# pylint: disable=invalid-metaclass
-class OWPythonScript(widget.OWWidget, metaclass=OWPythonScriptMeta):
+
+class OWPythonScript(widget.OWWidget):
     name = "Python Script"
     description = "Write a Python script and run it on input data or models."
     icon = "icons/PythonScript.svg"
     priority = 3150
 
-    # Signals are set up in the meta class
+    input_signals = (("data", Table), ("learner", Learner),
+                     ("classifier", Model), ("object", object))
+    input_names = ["in_" + name for name, _ in input_signals]
+
+    output_signals = input_signals
+    output_names = ["out_" + name for name, _ in output_signals]
+
+    def signal_handler(self, obj, id=None, signal=None):
+        id = id[0]
+        dic = getattr(self, signal)
+        if obj is None:
+            if id in dic.keys():
+                del dic[id]
+        else:
+            dic[id] = obj
+
+    Inputs, Outputs = _create_signals(signal_handler,
+                                      input_signals, output_signals)
 
     libraryListSource = \
         Setting([Script("Hello world", "print('Hello world')\n")])

Orange/widgets/tests/base.py

@@ -2,6 +2,7 @@
 import os
 import time
 import unittest
+import inspect
 from unittest.mock import Mock
 
 import numpy as np
@@ -196,7 +197,7 @@ def send_signal(self, input, value, *args, widget=None, wait=-1):
 
         Parameters
         ----------
-        input_name : str
+        input : str
         value : Object
         id : int
             channel id, used for inputs with flag Multiple
@@ -215,7 +216,11 @@ def send_signal(self, input, value, *args, widget=None, wait=-1):
             else:
                 raise ValueError("'{}' is not an input name for widget {}"
                                  .format(input, type(widget).__name__))
-        getattr(widget, input.handler)(value, *args)
+        handler = getattr(widget, input.handler)
+        if "signal" in inspect.signature(handler).parameters:
+            handler(value, *args, signal=input.name)
+        else:
+            handler(value, *args)
         widget.handleNewSignals()
         if wait >= 0 and widget.isBlocking():
             spy = QSignalSpy(widget.blockingStateChanged)