switch results to different pipe

[Almenon]

It simplifies the code if results come in on a different pipe and also that way prints don't interfere with the results.

To fix Almenon/AREPL-vscode#327

[Almenon]

I tried adding another pipe but all I/O stopped working... great :(

First I tried [process.stdin, process.stdout, process.stderr, 'pipe']
Then I tried ['pipe', 'pipe', 'pipe', 'pipe'] - no dice either

Maybe I should just try getting custom pipes working with stdout/stdin first and then expand.

[Almenon]

fileno docs: https://www.tutorialspoint.com/python/file_fileno.htm
pipe: https://docs.python.org/3.8/library/os.html?highlight=pipes#os.pipe
fdopen: https://docs.python.org/3.8/library/os.html?highlight=pipes#os.fdopen

[Almenon]

https://2ality.com/2018/05/child-process-streams.html
nodejs/node-v0.x-archive#5727

[Almenon]

dump got a error because the result_stream object is None ~ possibly because result_stream is only initialized if arepl_python_evaluator is executed directly. I tried moving the opening of the stream to the print_output function using with open(3,'w') as f but unlike regular files once you close the stream you can't open it again. Then I tested opening it without closing but same problem - I'm guessing when the function exits the object is garbage collected and close is called.

I need to somehow have the stream be a global object shared with dump.

[Almenon]

Note that when I run the test I got:

C:\dev\AREPL-backend>npm test

> arepl-backend@1.3.7 test C:\dev\AREPL-backend
> mocha -r ts-node/register --ui tdd *.test.ts --exit



  python_evaluator Tests
Starting Python...
    1) "before all" hook


  0 passing (229ms)
  1 failing

  1) python_evaluator Tests
       "before all" hook:
     Uncaught TypeError: self.stderrParser is not a function
      at C:\dev\AREPL-backend\node_modules\python-shell\index.ts:395:68
      at Array.forEach (<anonymous>)
      at PythonShell.receiveInternal (node_modules\python-shell\index.ts:393:15)
      at PythonShell.receiveStderr (node_modules\python-shell\index.ts:374:21)
      at Socket.<anonymous> (node_modules\python-shell\index.ts:153:22)
      at addChunk (_stream_readable.js:288:12)
      at readableAddChunk (_stream_readable.js:269:11)
      at Socket.Readable.push (_stream_readable.js:224:10)
      at Pipe.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)

Python-shell fails because this.stderr is true so it listens to data event of stderr and calls receiveStderr which calls recieveInternal which calls stderrParser but stderrParser is null due to binary mode. I'll have to either fix it or adapt my code.

[Almenon]

Here is an overview of what got changed by this pull request:

Issues
======
+ Solved 2
- Added 2
           

Complexity increasing per file
==============================
- python/arepl_python_evaluator.py  2
- python/arepl_result_stream.py  1
         

See the complete overview on Codacy

[Almenon]

Other changes this PR introduces:

• showGlobalVars renamed to show_global_vars for consistency
• changed to binary mode to avoid python-shell parsing mucking things up Fixes Incorrect stdout buffering mode #118
• updated node types to v12
• updated python-shell to v2
• a whole bunch of linting
• sys.stdout re-initialized in python to use line buffering fixes Incorrect stdout buffering mode #118

[Almenon]

🎉 This PR is included in version 1.3.9 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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