Duplexer confusing example

[Rybadour]

I'd recommend changing the challenge to use anything else but child_process. Seeing stdin and stdout as the arguments can give people false confidence of duplexer. I just spend an hour trying to figure out the next challenge only to find out that the order of duplexer is Writable, Readable. I know the documentation says that but other people made the same mistake: #55

I'd bet it help other people too if this challenge used process.stdin/stdout instead or something like reading from files.

[lyzadanger]

+1 on this. The confusing element for me here isn't duplexer's argument order necessarily (which are explicitly mentioned in the instructions), but that child_process.stdin is a Writeable stream (as opposed to process.stdin, which is a Readable stream) and child_process.stdout which is likewise flipped from process.stdout. So I struggled for a while with

return duplexer(childProcess.stdout, childProcess.stdin);

Because I didn't realize that child_process flipped the stdin/stdout stream types (not because I didn't grok that the Writeable should come first).

At the very least perhaps a heads up to this little twist in child_process?

[Ryan1729]

I also found myself confused as to why

return duplexer(childProcess.stdout, childProcess.stdin);

didn't work.

[famousgarkin]

+1

[Sequoia]

the confusion here stems from the following:

• process.stdin: 📖 Readable stream
• process.stdout: 📝 Writable stream
• childProc.stdin: 📝 Writable stream
• childProc.stdout: 📖 Readable stream

for process you're inside the process to stdin is readable to you, for child process you're outside so that process's stdin is writable to you.

[klarkc]

+1 The @Sequoia explanation must be in the documentation.

[mganuci]

Thank you @Sequoia for the explanation, I got confused as well. However, even the reference solution doesn't work due to a unit test failing

not ok 3 should be equal
  ---
    operator: equal
    expected:
      'ihrl\nibza\nipzjbpa\nillasl\nillasl\nihghhy\nivvw\nillw\nillw\nibza\nibn\
nilla\nifghuapul\nive'
    actual:
      'ihrl\nibza'
  ...

[kalinchernev]

Nice discussion, definitely worth having the explanation from @Sequoia in the exercise to be accessible to anyone going through the problem. Opened a PR to include these additions in the hints.

[ccarruitero]

Closing since changes was added in #196