repl: make last error available as `_error` by addaleax · Pull Request #18919 · nodejs/node · GitHub

This is pretty useful when trying to inspect the last
error caught by a REPL, and is made to be analogous to _,
which contains the last successful completion value.

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

Affected core subsystem(s)

repl

CI: https://ci.nodejs.org/job/node-test-commit/16425/

Is there any way we could add a Changes section for this?

@evanlucas done!

Would it be a good idea to make it something... less likely to conflict? __err or a symbol?

@Fishrock123 How would _err occur naturally in the REPL? I’m open to bikeshedding for the name, but a Symbol would defeat the purpose of making this value easily accessible.

love it

Love the idea, needs a better name. Two underscores is better than one and would prefer something like __lastError (that is, slightly more descriptive and not abbreviated)

@jasnell I think the main goal for the name is that it’s supposed to be typable really, really easily and quickly.

I love verbose names in real code, because we’re writing it for the 100 readers coming after us, but the REPL has the exact opposite goal of that: It’s code that’s only written once, ever, and never read by anybody else more than a minute after it was written. It’s not about choosing good or descriptive variable names in any way, it’s about being easy to write, so I would really prefer to keep it short and succinct.

(Literally all REPLs that I know of use _ or ans for the last value for those very reasons.)

The only thing I’m worried about here is discoverability, because right now you’d have to hear about it somewhere or read the docs. I’ve gone with _err because that’s one of the things I’d type to see whether this feature exists; __lastError is not on that list.

I’m also not worried about collisions; there is an explicit warning text being emitted here if that happens, like it is for _.

LGTM with either name.

@addaleax ... then how about meeting in the middle with _error?

@jasnell I’m fine with that, but honestly, I’m just going to write _err<TAB> every time. 😄

I’ve switched it for now but it might be helpful to know what your concerns actually are.

The concern is that I'm not particularly fond of abbreviated things.

How about $err? The $ prefix would be consistent with other command line APIs.

This is pretty useful when trying to inspect the last error caught by a REPL, and is made to be analogous to `_`, which contains the last successful completion value.

@TimothyGu I think @jasnell would want that to be $error ;) I would kind of like to be consistent with _ too, though…

CI https://ci.nodejs.org/job/node-test-pull-request/13431/

It seems like the CI run here was started for a different PR.

CI: https://ci.nodejs.org/job/node-test-commit/16599/

Landed in a8b5192

This is pretty useful when trying to inspect the last error caught by a REPL, and is made to be analogous to `_`, which contains the last successful completion value. PR-URL: #18919 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Evan Lucas <evanlucas@me.com> Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Prince John Wesley <princejohnwesley@gmail.com> Reviewed-By: Shingo Inoue <leko.noor@gmail.com>

This is pretty useful when trying to inspect the last error caught by a REPL, and is made to be analogous to `_`, which contains the last successful completion value. PR-URL: nodejs#18919 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Evan Lucas <evanlucas@me.com> Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Prince John Wesley <princejohnwesley@gmail.com> Reviewed-By: Shingo Inoue <leko.noor@gmail.com>

Should this be backported to v8.x-staging? If yes please follow the guide and raise a backport PR, if not let me know or add the dont-land-on label.

This is pretty useful when trying to inspect the last error caught by a REPL, and is made to be analogous to `_`, which contains the last successful completion value. PR-URL: nodejs#18919 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Evan Lucas <evanlucas@me.com> Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Prince John Wesley <princejohnwesley@gmail.com> Reviewed-By: Shingo Inoue <leko.noor@gmail.com>

nodejs-github-bot added the repl Issues and PRs related to the REPL subsystem. label Feb 21, 2018

cjihrig approved these changes Feb 21, 2018

View reviewed changes

evanlucas approved these changes Feb 21, 2018

View reviewed changes

vdeturckheim approved these changes Feb 21, 2018

View reviewed changes

BridgeAR added the author ready PRs that have at least one approval, no outstanding review comments, and a CI started. label Feb 22, 2018

targos approved these changes Feb 22, 2018

View reviewed changes

addaleax removed the author ready PRs that have at least one approval, no outstanding review comments, and a CI started. label Feb 22, 2018

tniessen approved these changes Feb 23, 2018

View reviewed changes

devsnek approved these changes Feb 26, 2018

View reviewed changes

addaleax force-pushed the repl-last-error branch from 0bb0ec2 to 1aaf085 Compare February 26, 2018 20:41

addaleax added 3 commits February 26, 2018 22:23

repl: make last error available as _error

ac6f5dd

This is pretty useful when trying to inspect the last error caught by a REPL, and is made to be analogous to `_`, which contains the last successful completion value.

[squash] add changes: section

fb8b01f

[squash] switch to error

1867690

addaleax changed the title repl: make last error available as _err repl: make last error available as _error Feb 26, 2018

addaleax force-pushed the repl-last-error branch from 1aaf085 to 1867690 Compare February 26, 2018 21:23

BridgeAR approved these changes Mar 2, 2018

View reviewed changes

BridgeAR added the author ready PRs that have at least one approval, no outstanding review comments, and a CI started. label Mar 2, 2018

jasnell approved these changes Mar 2, 2018

View reviewed changes

princejwesley approved these changes Mar 2, 2018

View reviewed changes

Leko approved these changes Mar 3, 2018

View reviewed changes

addaleax closed this Mar 4, 2018

addaleax removed the author ready PRs that have at least one approval, no outstanding review comments, and a CI started. label Mar 4, 2018

MylesBorins mentioned this pull request Mar 6, 2018

v9.8.0 proposal #19181

Merged

MylesBorins added dont-land-on-v6.x labels Apr 13, 2018

addaleax added the semver-minor PRs that contain new features and should be released in the next minor version. label May 2, 2018

addaleax deleted the repl-last-error branch May 2, 2018 16:32

repl: make last error available as `_error` by addaleax · Pull Request #18919 · nodejs/node · GitHub

Uh oh!

Uh oh!

repl: make last error available as _error - #18919

repl: make last error available as _error#18919addaleax wants to merge 3 commits intonodejs:masternodejs/node:masterfrom addaleax:repl-last-erroraddaleax/node:repl-last-errorCopy head branch name to clipboard

Conversation

addaleax commented Feb 21, 2018

Checklist

Affected core subsystem(s)

Uh oh!

addaleax commented Feb 21, 2018

Uh oh!

evanlucas Feb 21, 2018

Choose a reason for hiding this comment

Uh oh!

addaleax Feb 21, 2018

Choose a reason for hiding this comment

Uh oh!

Fishrock123 commented Feb 21, 2018

Uh oh!

addaleax commented Feb 21, 2018

Uh oh!

vdeturckheim left a comment

Choose a reason for hiding this comment

Uh oh!

jasnell commented Feb 22, 2018

Uh oh!

addaleax commented Feb 22, 2018 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

tniessen left a comment

Choose a reason for hiding this comment

Uh oh!

jasnell commented Feb 26, 2018

Uh oh!

addaleax commented Feb 26, 2018

Uh oh!

jasnell commented Feb 26, 2018

Uh oh!

TimothyGu commented Feb 26, 2018

Uh oh!

addaleax commented Feb 26, 2018

Uh oh!

BridgeAR commented Mar 2, 2018

Uh oh!

addaleax commented Mar 2, 2018

Uh oh!

addaleax commented Mar 4, 2018

Uh oh!

MylesBorins commented Apr 13, 2018

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

15 participants

repl: make last error available as _error#18919
addaleax wants to merge 3 commits into
nodejs:masterfrom
addaleax:repl-last-error

addaleax commented Feb 22, 2018 •
edited
Loading