Customize execution in kernel

[avriLee]

Hi, all

• Description: We want to use the data from web page(frontend) in the code cell. Now we just know Comm and try to use it as following:

  • step 1: Click the SEND button in web page, register Comm, and send the excepted data: comm.send({'test': 0})
  • step 2: Receive msg:

    
    # modify the default execution
    # now the `test`  has not been defined, 
    # if used, throw err and print it in the output area.

@my_comm.on_msg def _recv(msg): try:

modify the default execution

    # add the `test` to codes(top) from code cell like:
    # ```Python
    # test = msg['content']['data']['test']
    # print test
    # ```
except AttributeError as e:
    pass

- 
  - _step b:_ 
![image](https://user-images.githubusercontent.com/22313470/34513457-5640dd54-f0a3-11e7-8052-ad86b83f8675.png)

- **_Q:_**
  - if we follow the way we mentioned above, i have no idea of 
    -  customizing the execution in kernel;
    - now that this could be registered when a [`extension`](http://jupyter-notebook.readthedocs.io/en/stable/extending/frontend_extensions.html) is loaded,  after clicking `SEND`, does it mean that we need to trigger the batch operations(install and enable via nbextension) like `bash` in click fn?
  - otherwise, is there any convenient way to recommend?

Thanks for your time and waiting for your reply!

[avriLee]

em,i tried it and found if we follow as i mentioned above, Comm is unnecessary, while customizing the execution of codes in kernel is the key. Here's my personal 'solution':

• step 1: prepare the template js file( use placeholder e.g. {code} ):

  require([
  'services/kernels/kernel'
  ], function(kernel) {
  kernel.Kernel.prototype._execute = kernel.Kernel.prototype.execute;
  kernel.Kernel.prototype.execute = function (code, callbacks, options) {
      // var str = 'foo = 0\n';
      var str = '{code}';
      code = str + code;
      return this._execute(code, callbacks, options);
  };
  });

• step 2: when triggered( e.g. clicking the button ), modify the template file
• step 3: trigger batch operation i.e. install & enable in nbextension
• output: worked as expected!( Aha, it seems like the super man )

So, it may evolve into: is there any public or recommended way to customize the execution?