I'd like `throw` expressions (a lot). I wouldn't use them for this, but I want them for many of the same reasons outlined in the C# case for them.
-- T.J. Crowder On Wed, Apr 12, 2017 at 1:10 AM, Ron Buckton <[email protected]> wrote: > I’d much rather see something more like C# 7’s throw expressions: > https://docs.microsoft.com/en-us/dotnet/articles/csharp/ > whats-new/csharp-7#throw-expressions > > > > ```js > > // original example > > fs.writeFile("message.txt", "Hello Node.js", err => err ? throw err : > console.log("The file has been saved."); > > > > // better example > > function choose(kind) { > > return kind === 0 ? choseZero() : kind === 1 ? chooseOne() : throw new > Error("out of range"); > > } > > ``` > > > > Ron > > > > *From:* es-discuss [mailto:[email protected]] *On Behalf Of *T.J. > Crowder > *Sent:* Tuesday, April 11, 2017 5:20 AM > *To:* Elie Rotenberg <[email protected]> > *Cc:* Нурбек <[email protected]>; es-discuss <[email protected]> > *Subject:* Re: throwif operator > > > > I don't think we need a new keyword for this, both because of Elie's point > about handling it with a `throwif` function, and because Node's callback > pattern is a bit old-fashioned in the world of promises and async/await. > Until the Node API is updated to support promises natively, you can use one > of the various "promisifying" libs to promisify the API: > > > > ```js > > const pfs = /*...promisified version of fs*/; > > ``` > > > > ...and then: > > > > ```js > > pfs.writeFile("message.txt", "Hello Node.js") > > .then(() => console.log("The file has been saved.")); > > ``` > > > > ...and like your original code snippet, it will (on recent versions) > terminate Node if you don't handle the error. > > > > Combined with `async`/`await`, it becomes even cleaner: > > > > ```js > > await pfs.writeFile("message.txt", "Hello Node.js"); > > console.log("The file has been saved."); > > ``` > > > > (Of course, that has to be within an `async` function.) > > > > -- T.J. Crowder > > > On Tue, Apr 11, 2017 at 1:15 PM, Elie Rotenberg <[email protected]> wrote: > > const throwIf = (fn) => (err, ...args) => { > > if(err) throw err; > > return fn(...args); > > }; > > > > ... > > > > fs.writeFile('message.txt', 'Hello Node.js', throwIf(() => > console.log('The file has been saved'))); > > > > > > No need to extend the language and preempt keywords with stuff you can > very easily implement in userland. > > I'm not even convinced such a construct would be a good idea anyway to > encourage rethrowing errors without thinking if it can be handled locally. > > > > On Tue, Apr 11, 2017 at 2:06 PM, Нурбек <[email protected]> wrote: > > An example from node.js documentation: > > fs.writeFile('message.txt', 'Hello Node.js', (err) => { > if (err) throw err; > console.log('The file has been saved!'); > }); > > This looks like a common way to handle errors when the first parameter is > an instance of Error. > > Yes, this line of code is short and easy to copy-paste. > But introducing something like this: > > fs.writeFile('message.txt', 'Hello Node.js', (err) => { > throwif err; > console.log('The file has been saved!'); > }); > > would make the code much cleaner and bring some sort of standart way to > handle such errors. > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.mozilla.org%2Flistinfo%2Fes-discuss&data=02%7C01%7Cron.buckton%40microsoft.com%7Cf2cf33458e3a466e917708d480d52f9b%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636275100507832377&sdata=BZKPMSUjyLwQJr8fNltJnVFt4%2F8wLcLqHop92DUoW1U%3D&reserved=0> > > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.mozilla.org%2Flistinfo%2Fes-discuss&data=02%7C01%7Cron.buckton%40microsoft.com%7Cf2cf33458e3a466e917708d480d52f9b%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636275100507832377&sdata=BZKPMSUjyLwQJr8fNltJnVFt4%2F8wLcLqHop92DUoW1U%3D&reserved=0> > > >
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