Add supporting for making a directory for the native kernel

IPython/kernel/kernelspec.py

@@ -1,72 +1,91
 import io
 import json
 import os
+import sys
 
 pjoin = os.path.join
 
 from IPython.utils.path import get_ipython_dir
 from IPython.utils.py3compat import PY3
 from IPython.utils.traitlets import HasTraits, List, Unicode
 
 USER_KERNEL_DIR = pjoin(get_ipython_dir(), 'kernels')
 
 if os.name == 'nt':
     programdata = os.environ.get('PROGRAMDATA', None)
     if programdata:
         SYSTEM_KERNEL_DIR = pjoin(programdata, 'ipython', 'kernels')
     else:  # PROGRAMDATA is not defined by default on XP.
         SYSTEM_KERNEL_DIR = None
 else:
     SYSTEM_KERNEL_DIR = "/usr/share/ipython/kernels"
     
 NATIVE_KERNEL_NAME = 'python3' if PY3 else 'python2'
 
 class KernelSpec(HasTraits):
     argv = List()
     display_name = Unicode()
     language = Unicode()
     codemirror_mode = Unicode()
     
     resource_dir = Unicode()
     
     def __init__(self, resource_dir, argv, display_name, language,
                  codemirror_mode=None):
         super(KernelSpec, self).__init__(resource_dir=resource_dir, argv=argv,
                 display_name=display_name, language=language,
                 codemirror_mode=codemirror_mode)
         if not self.codemirror_mode:
             self.codemirror_mode = self.language
     
     @classmethod
     def from_resource_dir(cls, resource_dir):
         kernel_file = os.path.join(resource_dir, 'kernel.json')
         with io.open(kernel_file, 'r', encoding='utf-8') as f:
             kernel_dict = json.load(f)
         return cls(resource_dir=resource_dir, **kernel_dict)
 
 def _is_kernel_dir(path):
     return os.path.isdir(path) and os.path.isfile(pjoin(path, 'kernel.json'))
 
 def _list_kernels_in(dir):
     if dir is None:
         return {}
+    if not os.path.isdir(dir):
+        os.makedirs(dir, mode=0o644)
     return {f.lower(): pjoin(dir, f) for f in os.listdir(dir)
                         if _is_kernel_dir(pjoin(dir, f))}
 
+def _make_native_kernel_dir():
+    path = pjoin(USER_KERNEL_DIR, NATIVE_KERNEL_NAME)
+    os.mkdir(path)
+    with io.open(pjoin(path, 'kernel.json'), 'w', encoding='utf-8') as f:
+        json.dump({'argv':[NATIVE_KERNEL_NAME, '-c',
+                           'from IPython.kernel.zmq.kernelapp import main; main()',
+                            '-f', '{connection_file}'],
+                   'display_name': 'Python 3' if PY3 else 'Python 2',
+                   'language': 'python',
+                   'codemirror_mode': {'name': 'python',
+                                       'version': sys.version_info[0]},
+                  },
+                  f)
+    # TODO: Copy icons into directory
+    return path
+
 def list_kernel_specs():
     """Returns a dict mapping kernels to resource directories."""
     d = _list_kernels_in(SYSTEM_KERNEL_DIR)
     d.update(_list_kernels_in(USER_KERNEL_DIR))
     
     if NATIVE_KERNEL_NAME not in d:
-        d[NATIVE_KERNEL_NAME] = ''  # TODO: native kernel resource directory
+        d[NATIVE_KERNEL_NAME] = _make_native_kernel_dir()
     return d
 
 def get_kernel_spec(kernel_name):
     """Returns a KernelSpec instance for the given kernel_name.
     
     Raises KeyError if the given kernel name is not found.
     """
     d = list_kernel_specs()
     resource_dir = d[kernel_name.lower()]
     return KernelSpec.from_resource_dir(resource_dir)
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