While its true most IDE's can search for references in strings, `nameof` takes some of the guesswork out of determining whether a substring that matches a symbol refers to the symbol or is merely part of the sentence.
That said, `nameof` is primarily a convenience for an IDE. Ron Sent from my Windows Phone ________________________________ From: Isiah Meadows<mailto:isiahmead...@gmail.com> Sent: 8/8/2015 8:57 PM To: Ron Buckton<mailto:ron.buck...@microsoft.com>; Behrang Saeedzadeh<mailto:behran...@gmail.com>; EcmaScript Discuss Mailing List<mailto:es-discuss@mozilla.org> Subject: Re: What do you think about a C# 6 like nameof() expression for JavaScript. To be honest, most larger IDEs also search for references in strings, and even if it doesn't, any decent editor can do a regex replace of `identifierName` without problem. I don't see much of a problem here. Also, do you know of any other language that has this at the syntax level (not macro)? On Sat, Aug 8, 2015, 23:12 Ron Buckton <ron.buck...@microsoft.com<mailto:ron.buck...@microsoft.com>> wrote: One of the main purposes of the `nameof` operator is to provide the string value of a symbol, so that if you perform a "Rename" refactoring of that symbol that the change is also reflected. This is primarily for cases where you perform precondition assertions tied to an argument: ``` ... static void Method(string x) { if (x == null) throw new ArgumentNullException(nameof(x)); ... } ``` Now, if I later rename `x`, I don't need to also find any string literals of "x" and manually update them. There are other uses of `nameof`, but they all boil down to roughly the same thing. Ron ________________________________ From: Isiah Meadows<mailto:isiahmead...@gmail.com> Sent: 8/8/2015 7:23 PM To: Behrang Saeedzadeh<mailto:behran...@gmail.com>; EcmaScript Discuss Mailing List<mailto:es-discuss@mozilla.org> Subject: Re: What do you think about a C# 6 like nameof() expression for JavaScript. Call me crazy, but I don't see anything that couldn't be done more concisely with a string literal. Is it supposed to be able to do this? ```js function foo(x) { return nameof(x); } foo(bar); // "bar"; ``` In that case, the engine would have to keep track of usages as well, in a similar sense as `arguments.callee`, and if it were a function, it would make optimization quite difficult, as engines don't have the capacity to statically analyze that such a function is used. If it is like `typeof`, we now have a breaking change - a keyword that was a valid Identifier before. ```js // Error? function nameof(value) { return value.name<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fvalue.name&data=01%7c01%7cron.buckton%40microsoft.com%7ca2e2c4d35400435810d008d2a061897d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=pwV45avF9RX6COETpoLIY4EF%2bmCVmk6kEEmLc2JXSCY%3d>; } var bar = {name: 2}; nameof(bar); // "bar" or 2? ``` I don't think this is going to work out in practice, not in ECMAScript proper. You might appreciate Sweet.js, though. On Sat, Aug 8, 2015, 21:27 Behrang Saeedzadeh <behran...@gmail.com<mailto:behran...@gmail.com>> wrote: Forgot to mention that nameof works with local variables too: function foo() { var aNum = 1; console.log(nameof(aNmum), aNum); } On Sat, Aug 8, 2015 at 10:38 AM Behrang Saeedzadeh <behran...@gmail.com<mailto:behran...@gmail.com>> wrote: So basically we could use it like this: function aFunc(aParam) { throw new Error(nameof(aParam)); } and nameof(aParam) would return the string "aParam". This is possible to do even right now using arguments.callee and some hacky code, but having it built-in to spec would be nicer IMHO. -- Best regards, Behrang Saeedzadeh -- Best regards, Behrang Saeedzadeh _______________________________________________ es-discuss mailing list es-discuss@mozilla.org<mailto:es-discuss@mozilla.org> https://mail.mozilla.org/listinfo/es-discuss<https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fmail.mozilla.org%2flistinfo%2fes-discuss&data=01%7c01%7cron.buckton%40microsoft.com%7ca2e2c4d35400435810d008d2a061897d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=7DHMx5gTd2OexSlKscSrKlMIxABMUkOKRC%2fuCbc6pWk%3d>
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