Backport PR #4016: fix IPython.start_* functions.

See gh-4005

IPython/kernel/zmq/tests/test_start_kernel.py

@@ -0,0 +1,17 b''
+import nose.tools as nt
+
+from .test_embed_kernel import setup, teardown, setup_kernel
+
+TIMEOUT = 15
+
+def test_ipython_start_kernel_userns():
+    cmd = ('from IPython import start_kernel\n'
+           'ns = {"tre": 123}\n'
+           'start_kernel(user_ns=ns)')
+    
+    with setup_kernel(cmd) as client:
+        msg_id = client.object_info('tre')
+        msg = client.get_shell_msg(block=True, timeout=TIMEOUT)
+        content = msg['content']
+        assert content['found']
+        nt.assert_equal(content['string_form'], u'123')
  No newline at end of file

IPython/core/shellapp.py

@@ -34,7 +34,7 b' from IPython.utils import py3compat'
 from IPython.utils.contexts import preserve_keys
 from IPython.utils.path import filefind
 from IPython.utils.traitlets import (
-    Unicode, Instance, List, Bool, CaselessStrEnum
+    Unicode, Instance, List, Bool, CaselessStrEnum, Dict
 )
 
 #-----------------------------------------------------------------------------
@@ -197,6 +197,12 b' class InteractiveShellApp(Configurable):'
         """
     )
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
+    
+    user_ns = Dict(default_value=None)
+    def _user_ns_changed(self, name, old, new):
+        if self.shell is not None:
+            self.shell.user_ns = new
+            self.shell.init_user_ns()
 
     def init_path(self):
         """Add current working directory, '', to sys.path"""

IPython/kernel/zmq/kernelapp.py

@@ -393,6 +393,7 b' class IPKernelApp(BaseIPythonApplication, InteractiveShellApp):'
                                 stdin_socket=self.stdin_socket,
                                 log=self.log,
                                 profile_dir=self.profile_dir,
+                                user_ns=self.user_ns,
         )
         kernel.record_ports(self.ports)
         self.kernel = kernel
@@ -458,6 +459,7 b' class IPKernelApp(BaseIPythonApplication, InteractiveShellApp):'
         except KeyboardInterrupt:
             pass
 
+launch_new_instance = IPKernelApp.launch_instance
 
 def main():
     """Run an IPKernel as an application"""

IPython/terminal/ipapp.py

@@ -334,7 +334,7 b' class TerminalIPythonApp(BaseIPythonApplication, InteractiveShellApp):'
         # so the banner shows *before* all extension loading stuff.
         self.shell = TerminalInteractiveShell.instance(parent=self,
                         display_banner=False, profile_dir=self.profile_dir,
-                        ipython_dir=self.ipython_dir)
+                        ipython_dir=self.ipython_dir, user_ns=self.user_ns)
         self.shell.configurables.append(self)
 
     def init_banner(self):