PR: Add command line option to connect to an existing kernel at startup (IPython console)

[Social-Mean]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

Issue(s) Resolved

Fixes #23130

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: Social-Mean

[ccordoba12]

Thanks @Social-Mean for your work on this!

[pep8speaks]

Hello @Social-Mean! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file spyder/plugins/ipythonconsole/plugin.py:

Line 563:77: W291 trailing whitespace

Comment last updated at 2025-01-15 17:34:01 UTC

[Social-Mean]

I need help! Spyder is not connected to the specific kernel. The reproduction process is as follows:

• Start an ipython kernel.

  (spyder-dev) $ python -m spyder_kernels.console
  

  This will output like:

  (spyder-dev) C:\Users\username>python -m spyder_kernels.console
  NOTE: When using the `ipython kernel` entry point, Ctrl-C will not work.
  
  To exit, you will have to explicitly quit this process, by either sending
  "quit" from a client, or using Ctrl-\ in UNIX-like environments.
  
  To read more about this, see https://github.com/ipython/ipython/issues/2049
  
  
  To connect another client to this kernel, use:
   --existing kernel-12345.json
  

  So we get the connection file is kernel-12345.json

• Start Spyder with --connect-to-kernel=kernel-*.json option (run the following command in a new terminal window):

  (spyder-dev) $ python bootstrap.py -- --connect-to-kernel=kernel-12345.json
  

Now Spyder can start normally, but a new kernel is created as before, instead of connecting to the specified kernel.

[ccordoba12]

@Social-Mean, last comments then this should be ready.

And about what you said:

Start Spyder with --connect-to-kernel=kernel-*.json option

You don't need to use = to pass command line options, so it needs to be

spyder --connect-to-kernel kernel-*.json

I tested that with my suggestion below and things are working as expected.

[ccordoba12]

Thanks for your work on this @Social-Mean!

Note: I added an entry to our Changelog to mention the small API change you did here.

[ccordoba12]

@meeseeksdev please backport to 6.x