[RFC] Add automated summaries

orangewidget/utils/signals.py

@@ -1,5 +1,6 @@
 import copy
 import itertools
+from functools import singledispatch
 
 from orangecanvas.registry.description import (
     InputSignal, OutputSignal, Single, Multiple, Default, NonDefault,
@@ -14,6 +15,11 @@
 _counter = itertools.count()
 
 
+@singledispatch
+def summarize(_):
+    return None, None
+
+
 class _Signal:
     @staticmethod
     def get_flags(multiple, default, explicit, dynamic):
@@ -76,23 +82,40 @@ def set_train_data(self, data):
     explicit (bool, optional):
         if set, this signal is only used when it is the only option or when
         explicitly connected in the dialog (default: `False`)
+    auto_summary (bool, optional):
+        decides whether this signal is used for auto_summary; only one signal
+        should set this to True. If left at default (`None`), the value is set
+        by `set_default_auto_summary`, which is called from the meta-class.
     """
     def __init__(self, name, type, id=None, doc=None, replaces=None, *,
-                 multiple=False, default=False, explicit=False):
+                 multiple=False, default=False, explicit=False,
+                 auto_summary=None):
         flags = self.get_flags(multiple, default, explicit, False)
         super().__init__(name, type, "", flags, id, doc, replaces or [])
+        self.auto_summary = auto_summary
         self._seq_id = next(_counter)
 
     def __call__(self, method):
         """
         Decorator that stores decorated method's name in the signal's
         `handler` attribute. The method is returned unchanged.
         """
+        def set_summary(widget, value, *args, **kwargs):
+            if self.auto_summary:
+                info = widget.info
+                if value is None:
+                    info.set_input_summary(info.NoInput)
+                else:
+                    summary, details = summarize(value)
+                    if summary is not None:
+                        info.set_input_summary(summary, details)
+            return method(widget, value, *args, **kwargs)
+
         if self.handler:
             raise ValueError("Input {} is already bound to method {}".
                              format(self.name, self.handler))
         self.handler = method.__name__
-        return method
+        return set_summary
 
 
 class Output(OutputSignal, _Signal):
@@ -133,12 +156,18 @@ class Outputs:
         of the declared type and that the output can be connected to any input
         signal which can accept a subtype of the declared output type
         (default: `True`)
+    auto_summary (bool, optional):
+        decides whether this signal is used for auto_summary; only one signal
+        should set this to True. If left at default (`None`), the value is set
+        by `set_default_auto_summary`, which is called from the meta-class. 
     """
     def __init__(self, name, type, id=None, doc=None, replaces=None, *,
-                 default=False, explicit=False, dynamic=True):
+                 default=False, explicit=False, dynamic=True,
+                 auto_summary=None):
         flags = self.get_flags(False, default, explicit, dynamic)
+        self.auto_summary = auto_summary
         super().__init__(name, type, flags, id, doc, replaces or [])
-        self.widget = None
+        self.widget = None  #: OWBaseWidget
         self._seq_id = next(_counter)
 
     def send(self, value, id=None):
@@ -147,6 +176,14 @@ def send(self, value, id=None):
         signal_manager = self.widget.signalManager
         if signal_manager is not None:
             signal_manager.send(self.widget, self.name, value, id)
+        info = self.widget.info
+        if self.auto_summary:
+            if value is None:
+                info.set_output_summary(info.NoOutput)
+            else:
+                summary, details = summarize(value)
+                if summary is not None:
+                    info.set_output_summary(summary, details)
 
     def invalidate(self):
         """Invalidate the current output value on the signal"""
@@ -257,6 +294,28 @@ def get_signals(cls, direction, ignore_old_style=False):
         signals = [signal for _, signal in getmembers(signal_class, _Signal)]
         return list(sorted(signals, key=lambda s: s._seq_id))
 
+    @classmethod
+    def set_default_auto_summary(cls):
+        """
+        Set the default auto_summary; called from meta class.
+
+        If
+        - there is only a single input/output, or there is a default signal,
+        - and that signal has auto_summary left at default (None),
+        - and no other signal has auto_summary set to True,
+        set that signal's auto_summary to True, so that it's value will be
+        shown in the status.
+        """
+        for signal_cls, signal_type in ((cls.Inputs, Input),
+                                        (cls.Outputs, Output)):
+            signals = getmembers(signal_cls, signal_type)
+            if any(signal.auto_summary for _, signal in signals):
+                continue
+            for _, signal in signals:
+                if signal.auto_summary is None:
+                    signal.auto_summary = \
+                        bool(signal.flags & Default) or len(signals) == 1
+
 
 class AttributeList(list):
     """Signal type for lists of attributes (variables)"""

orangewidget/widget.py

@@ -98,6 +98,7 @@ def __new__(mcs, name, bases, namespace, openclass=False, **kwargs):
         if not cls.name: # not a widget
             return cls
         cls.convert_signals()
+        cls.set_default_auto_summary()
         cls.settingsHandler = \
             SettingsHandler.create(cls, template=cls.settingsHandler)
         return cls