Merge pull request #35 from minrk/ipywidgets-hardcode-extension

use ipywidgets as an extension

Author: minrk

ipykernel/ipkernel.py

@@ -60,14 +60,6 @@ def __init__(self, **kwargs):
         self.comm_manager = CommManager(shell=self.shell, parent=self,
                                         kernel=self)
 
-        # BEGIN HARDCODED WIDGETS HACK
-        try:
-            from ipywidgets import handle_kernel
-            handle_kernel(self)
-        except ImportError:
-            self.log.debug('ipywidgets package not installed.  Widgets will not be available.')
-        # END HARDCODED WIDGETS HACK
-
         self.shell.configurables.append(self.comm_manager)
         comm_msg_types = [ 'comm_open', 'comm_msg', 'comm_close' ]
         for msg_type in comm_msg_types:

ipykernel/kernelapp.py

@@ -342,6 +342,18 @@ def init_shell(self):
         self.shell = getattr(self.kernel, 'shell', None)
         if self.shell:
             self.shell.configurables.append(self)
+    
+    def init_extensions(self):
+        super(IPKernelApp, self).init_extensions()
+        # BEGIN HARDCODED WIDGETS HACK
+        # Ensure ipywidgets extension is loaded if available
+        extension_man = self.shell.extension_manager
+        if 'ipywidgets' not in extension_man.loaded:
+            try:
+                extension_man.load_extension('ipywidgets')
+            except ImportError as e:
+                self.log.debug('ipywidgets package not installed.  Widgets will not be available.')
+        # END HARDCODED WIDGETS HACK
 
     @catch_config_error
     def initialize(self, argv=None):