add IPython.lib.kernel

get_connection_info and connect_qtconsole are now implemented as library functions
in the new module.  The zmqshell magics that call them are now simple wrappers.

IPython/lib/kernel.py

@@ -0,0 +1,99 @@
+"""Utilities for connecting to kernels
+
+Authors:
+
+* Min Ragan-Kelley
+
+"""
+
+#-----------------------------------------------------------------------------
+#  Copyright (C) 2011  The IPython Development Team
+#
+#  Distributed under the terms of the BSD License.  The full license is in
+#  the file COPYING, distributed as part of this software.
+#-----------------------------------------------------------------------------
+
+#-----------------------------------------------------------------------------
+# Imports
+#-----------------------------------------------------------------------------
+
+import json
+import sys
+from subprocess import Popen, PIPE
+
+from IPython.utils.path import filefind
+from IPython.utils.py3compat import str_to_bytes
+
+
+#-----------------------------------------------------------------------------
+# Functions
+#-----------------------------------------------------------------------------
+
+def get_connection_file(app=None):
+    """Return the path to the connection file of an app
+    
+    Parameters
+    ----------
+    app : KernelApp instance [optional]
+        If unspecified, the currently running app will be used
+    """
+    if app is None:
+        from IPython.zmq.kernelapp import KernelApp
+        if not KernelApp.initialized():
+            raise RuntimeError("app not specified, and not in a running Kernel")
+
+        app = KernelApp.instance()
+    return filefind(app.connection_file, ['.', app.profile_dir.security_dir])
+
+def get_connection_info(unpack=False):
+    """Return the connection information for the current Kernel.
+    
+    Parameters
+    ----------
+    unpack : bool [default: False]
+        if True, return the unpacked dict, otherwise just the string contents
+        of the file.
+    
+    Returns
+    -------
+    The connection dictionary of the current kernel, as string or dict,
+    depending on `unpack`.
+    """
+    cf = get_connection_file()
+    with open(cf) as f:
+        info = f.read()
+
+    if unpack:
+        info = json.loads(info)
+        # ensure key is bytes:
+        info['key'] = str_to_bytes(info.get('key', ''))
+    return info
+
+def connect_qtconsole(argv=None):
+    """Connect a qtconsole to the current kernel.
+    
+    This is useful for connecting a second qtconsole to a kernel, or to a
+    local notebook.
+    
+    Parameters
+    ----------
+    argv : list [optional]
+        Any extra args to be passed to the console.
+    
+    Returns
+    -------
+    subprocess.Popen instance running the qtconsole frontend
+    """
+    argv = [] if argv is None else argv
+
+    # get connection file from current kernel
+    cf = get_connection_file()
+
+    cmd = ';'.join([
+        "from IPython.frontend.qt.console import qtconsoleapp",
+        "qtconsoleapp.main()"
+    ])
+
+    return Popen([sys.executable, '-c', cmd, '--existing', cf] + argv, stdout=PIPE, stderr=PIPE)
+
+

IPython/zmq/zmqshell.py

@@ -31,9 +31,13 @@
 from IPython.core.macro import Macro
 from IPython.core.magic import MacroToEdit
 from IPython.core.payloadpage import install_payload_page
+from IPython.lib.kernel import (
+    get_connection_file, get_connection_info, connect_qtconsole
+)
 from IPython.utils import io
 from IPython.utils.jsonutil import json_clean
 from IPython.utils.path import get_py_filename
+from IPython.utils.process import arg_split
 from IPython.utils.traitlets import Instance, Type, Dict, CBool
 from IPython.utils.warn import warn, error
 from IPython.zmq.displayhook import ZMQShellDisplayHook, _encode_binary
@@ -442,26 +446,22 @@ def magic_connect_info(self, arg_s):
         $> ipython <app> --existing
         
         """
-        from IPython.zmq.kernelapp import KernelApp
-        if not KernelApp.initialized():
-            error("KernelApp is not initialized. I cannot find the connection info")
-            return
-        app = KernelApp.instance()
         try:
-            with open(app.connection_file) as f:
-                s = f.read()
+            connection_file = get_connection_file()
+            info = get_connection_info(unpack=False)
         except Exception as e:
-            error("Could not read connection file: %s" % e)
+            error("Could not get connection info: %r" % e)
             return
-        print (s + '\n')
+
+        print (info + '\n')
         print ("Paste the above JSON into a file, and connect with:\n"
             "    $> ipython <app> --existing <file>\n"
             "or, if you are local, you can connect with just:\n"
             "    $> ipython <app> --existing %s\n"
             "or even just:\n"
             "    $> ipython <app> --existing\n"
             "if this is the most recent IPython session you have started."
-            % os.path.basename((app.connection_file))
+            % os.path.basename(connection_file)
         )
 
     def magic_qtconsole(self, arg_s):
@@ -470,20 +470,12 @@ def magic_qtconsole(self, arg_s):
         Useful for connecting a qtconsole to running notebooks, for better
         debugging.
         """
-        from IPython.zmq.kernelapp import KernelApp
-
-        if not KernelApp.initialized():
-            error("KernelApp is not initialized. %qtconsole magic must be run from a Kernel")
+        try:
+            p = connect_qtconsole(arg_split(arg_s, os.name=='posix'))
+        except Exception as e:
+            error("Could not start qtconsole: %r" % e)
             return
-        app = KernelApp.instance()
-
-        cmd = ';'.join([
-            "from IPython.frontend.qt.console import qtconsoleapp",
-            "qtconsoleapp.main()"
-        ])
 
-        return Popen([sys.executable, '-c', cmd, '--existing', app.connection_file],
-            stdout=PIPE,stderr=PIPE)
 
     def set_next_input(self, text):
         """Send the specified text to the frontend to be presented at the next