New in version 3.0.
You can now re-use the kernel machinery in IPython to easily make new kernels. This is useful for languages that have Python bindings, such as Octave (via Oct2Py), or languages where the REPL can be controlled in a tty using pexpect, such as bash.
See also
Subclass IPython.kernel.zmq.kernelbase.Kernel, and implement the following methods and attributes:
Information for msging_kernel_info replies. ‘Implementation’ refers to the kernel (e.g. IPython), and ‘language’ refers to the language it interprets (e.g. Python). The ‘banner’ is displayed to the user in console UIs before the first prompt. All of these values are strings.
Language information for msging_kernel_info replies, in a dictionary. This should contain the key mimetype with the mimetype of code in the target language (e.g. 'text/x-python'), and file_extension (e.g. 'py'). It may also contain keys codemirror_mode and pygments_lexer if they need to differ from language.
Other keys may be added to this later.
Execute user code.
Parameters: |
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Your method should return a dict containing the fields described in execution_results. To display output, it can send messages using send_response(). See Messaging in IPython for details of the different message types.
To launch your kernel, add this at the end of your module:
if __name__ == '__main__':
from IPython.kernel.zmq.kernelapp import IPKernelApp
IPKernelApp.launch_instance(kernel_class=MyKernel)
echokernel.py will simply echo any input it’s given to stdout:
from IPython.kernel.zmq.kernelbase import Kernel
class EchoKernel(Kernel):
implementation = 'Echo'
implementation_version = '1.0'
language = 'no-op'
language_version = '0.1'
language_info = {'mimetype': 'text/plain'}
banner = "Echo kernel - as useful as a parrot"
def do_execute(self, code, silent, store_history=True, user_expressions=None,
allow_stdin=False):
if not silent:
stream_content = {'name': 'stdout', 'text': code}
self.send_response(self.iopub_socket, 'stream', stream_content)
return {'status': 'ok',
# The base class increments the execution count
'execution_count': self.execution_count,
'payload': [],
'user_expressions': {},
}
if __name__ == '__main__':
from IPython.kernel.zmq.kernelapp import IPKernelApp
IPKernelApp.launch_instance(kernel_class=EchoKernel)
Here’s the Kernel spec kernel.json file for this:
{"argv":["python","-m","echokernel", "-f", "{connection_file}"],
"display_name":"Echo"
}
You can override a number of other methods to improve the functionality of your kernel. All of these methods should return a dictionary as described in the relevant section of the messaging spec.
Code completion
Parameters: |
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See also
msging_completion messages
Object introspection
Parameters: |
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See also
msging_inspection messages
History access. Only the relevant parameters for the type of history request concerned will be passed, so your method definition must have defaults for all the arguments shown with defaults here.
See also
msging_history messages
Is code entered in a console-like interface complete and ready to execute, or should a continuation prompt be shown?
Parameters: | code (str) – The code entered so far - possibly multiple lines |
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See also
msging_is_complete messages
Shutdown the kernel. You only need to handle your own clean up - the kernel machinery will take care of cleaning up its own things before stopping.
Parameters: | restart (bool) – Whether the kernel will be started again afterwards |
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See also
msging_shutdown messages