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Support 'throw' expressions #18535

Closed as not planned
Closed as not planned
Support 'throw' expressions#18535
Labels
ES NextNew featurers for ECMAScript (a.k.a. ESNext)SuggestionAn idea for TypeScriptWaiting for TC39Unactionable until TC39 reaches some conclusion

Description

@brn
Taketoshi Aono (brn)
opened on Sep 17, 2017

Support proposal-throw-expressions.
That proposal is now stage-1, but worth to implements for convenience and this proposal not break backward-compatibilities.

Current

ts

const errorThrowExp = () => { throw new Error('Error!'); }
function errorThrowFn(maybeTrue) {
  if (maybeTrue){ 
    return ...;
  } else {
    throw new Error('Error!');
  }
}

js

const errorThrowExp = function() {throw new Error('Error!')}
function errorThrowFn(maybeTrue) {
  if (maybeTrue){ 
    return ...;
  } else {
    throw new Error('Error!');
  }
}

Proposal

ts

const errorThrower = () => throw new Error('Error!');
function errorThrowFn(maybeTrue: boolean) {
  return maybeTrue? ...: throw new Error('Error!');
}

js

const errorThrower = function() { throw new Error('Error!'); }
function errorThrowFn(maybeTrue: boolean) {
  return maybeTrue? ...: (function() { throw new Error('Error!') })();
}

Activity

  1. kitsonk commented on Sep 17, 2017

    @kitsonk
    Kitson Kelly (kitsonk)
    on Sep 17, 2017
    Contributor

    Just to note, Ron Buckton (@rbuckton) is closely aligned to the TypeScript team. I highly suspect this proposal would be implemented when everyone is comfortable it is in a stable enough position.

  2. brn commented on Sep 17, 2017

    @brn
    Taketoshi Aono (brn)
    on Sep 17, 2017
    Author

    Kitson Kelly (@kitsonk) That make sense.
    So is this proposal premature?

  3. Daniel Rosenwasser (DanielRosenwasser)
    added
    ES NextNew featurers for ECMAScript (a.k.a. ESNext)
    SuggestionAn idea for TypeScript
    on Sep 17, 2017
  4. Daniel Rosenwasser (DanielRosenwasser)
    changed the title [-]Support throw-expressions[/-] [+]Support 'throw' Expressions[/+] on Sep 17, 2017
  5. Daniel Rosenwasser (DanielRosenwasser)
    changed the title [-]Support 'throw' Expressions[/-] [+]Support 'throw' expressions[/+] on Sep 17, 2017

  6. DanielRosenwasser commented on Sep 17, 2017

    @DanielRosenwasser
    Daniel Rosenwasser (DanielRosenwasser)
    on Sep 17, 2017
    Member

    So is this proposal premature?

    Nope, it's fine to track it here. Like Kitson Kelly (@kitsonk) said, Ron Buckton (@rbuckton) is championing it and is part of our team, but we will need it to reach a later stage before adopting it in TypeScript.

    For what it's worth, I'd be willing to bet he has a branch with an implementation of throw-expressions. 😄

  7. rbuckton commented on Sep 18, 2017

    @rbuckton
    Ron Buckton (rbuckton)
    on Sep 18, 2017
    Contributor

    https://github.com/Microsoft/TypeScript/tree/throwOperator?files=1

    Currently it does not yet support unreachability checks at the expression level. Also, I am waiting for the next TC39 meeting to see if the proposal moves to Stage 2.

  8. brn commented on Sep 18, 2017

    @brn
    Taketoshi Aono (brn)
    on Sep 18, 2017
    Author

    Daniel Rosenwasser (@DanielRosenwasser) Ron Buckton (@rbuckton)
    I got it.
    Thank you for the detailed explanation!

  9. Yogu commented on May 11, 2018

    @Yogu
    Jan Melcher (Yogu)
    on May 11, 2018
    Contributor

    The proposal is now in stage 2 - would be cool if this gets implemented in TypeScript.

  10. rbuckton commented on May 12, 2018

    @rbuckton
    Ron Buckton (rbuckton)
    on May 12, 2018
    Contributor

    TypeScript's current stance is that we will not adopt a proposed JavaScript feature until it has reached Stage 3. Currently, Stage 3 for throw expressions is blocked from advancement due to overlap with the do expressions proposal.

  11. Yogu commented on May 12, 2018

    @Yogu
    Jan Melcher (Yogu)
    on May 12, 2018
    Contributor

    Ah, I see. Thanks, Ron Buckton (@rbuckton)!

  12. Ryan Cavanaugh (RyanCavanaugh)
    added
    Waiting for TC39Unactionable until TC39 reaches some conclusion
    on Aug 15, 2018

  13. lufzle commented on Jun 24, 2019

    @lufzle
    Dario Farzati (lufzle)
    on Jun 24, 2019

    This is now in stage 3 :)

  14. rbuckton commented on Jun 24, 2019

    @rbuckton
    Ron Buckton (rbuckton)
    on Jun 24, 2019
    Contributor

    No, this has not yet advanced to Stage 3.

  15. microsoft
    locked and limited conversation to collaborators on Jun 25, 2019

  16. RyanCavanaugh commented on Mar 15, 2024

    @RyanCavanaugh
    Ryan Cavanaugh (RyanCavanaugh)
    on Mar 15, 2024
    Member

    Closing since there's nothing for us to do but wait for TC39

  17. Ryan Cavanaugh (RyanCavanaugh)
    closed this as not plannedon Mar 15, 2024
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