Discuss
  • Has there ever been discussion around a python-like "with" syntax?

Has there ever been discussion around a python-like "with" syntax?

# Dan Aprahamian (7 years ago)

Hello all! First time posting here. I was curious if there was ever talk about adding something similar to python's with syntax to JS. Obviously we already have a "with" keyword, but I figure we could probably use "use" as the keyword instead. I was thinking something like

// Some user defined resource that can be "entered" and "exited"
class MyResource {
  // Function called when entered
  async [Symbol.enter]() {
  }

  // Function called when exited
  [Symbol.exit]() {
  }
}

const resource = new MyResource();

async function useResource() {
  use myResource {
    // Inside here, resource has had "enter" called on it

    await doSomethingAsync();
    // Once this block is finished executing (including async)
    // exit is called
  }
  // exit has been called now
}

Use would effectively be the equivalent of:

async function use(resource, body) {
  await resource[Symbol.enter]();
  try {
    await body();
  } finally {
    await resource[Symbol.exit]();
  }
}

Has something like this been considered before?

Thanks, Dan

# Till Schneidereit (7 years ago)

Ron Buckton has a proposal that's quite similar to what you're talking about: tc39/proposal

# Michael J. Ryan (7 years ago)

I was going to mention C#'s using statement as well... though I do like the use of a symbol over Ron's proposal, I think using might be a better approach.

# Dan Aprahamian (7 years ago)

Sorry for spamming, forgot to edit subject line.

Anyway, is there a good way to get involved with tc39/proposal-using-statement?

Thanks, Dan

# Isiah Meadows (7 years ago)

It's usually as simple as just reading it and filing issues/suggestions. IIRC there's a CONTRIBUTING.md in the repo that redirects to TC39's main document, and that could help you.