Ensure the channel is the same as the widget's ID, if no default chan…

…nel is given at init time.

src/invent/ui/core/component.py

@@ -476,35 +476,6 @@ def update_attribute(self, attribute_name, attribute_value):
         else:
             self.element.removeAttribute(attribute_name)
 
-    def when(self, subject, to_channel=None, do=None):
-        """
-        Convenience method for wrapping subscriptions.
-
-        If no "do" handler is given, we assume this function is decorating the
-        handler to "do" the stuff.
-
-        The subject and to_channel can be either individual strings or a
-        list of strings to indicate the channel[s] and message subject[s] to
-        match.
-        """
-        if not to_channel:
-            to_channel = self.id
-
-        if do:
-            invent.subscribe(
-                handler=do, to_channel=to_channel, when_subject=subject
-            )
-        else:
-
-            def inner_function(handler):
-                invent.subscribe(
-                    handler=handler,
-                    to_channel=to_channel,
-                    when_subject=subject,
-                )
-
-            return inner_function
-
 
 class Widget(Component):
     """
@@ -530,6 +501,11 @@ class Widget(Component):
         default_value=None,
     )
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        if self.channel is None:
+            self.channel = self.id
+
     def publish(self, blueprint, **kwargs):
         """
         Given the name of one of the class's MessageBlueprints, publish
@@ -549,6 +525,35 @@ def publish(self, blueprint, **kwargs):
             )
             invent.publish(message, to_channel=channels)
 
+    def when(self, subject, to_channel=None, do=None):
+        """
+        Convenience method for wrapping subscriptions.
+
+        If no "do" handler is given, we assume this function is decorating the
+        handler to "do" the stuff.
+
+        The subject and to_channel can be either individual strings or a
+        list of strings to indicate the channel[s] and message subject[s] to
+        match.
+        """
+        if not to_channel:
+            to_channel = self.id
+
+        if do:
+            invent.subscribe(
+                handler=do, to_channel=to_channel, when_subject=subject
+            )
+        else:
+
+            def inner_function(handler):
+                invent.subscribe(
+                    handler=handler,
+                    to_channel=to_channel,
+                    when_subject=subject,
+                )
+
+            return inner_function
+
 
 class Container(Component):
     """