A module namespace isn’t an instance of `Module`, it’s a module namespace spec object. If it has a `name` member, that is because the module you imported has an exported binding called `name`. But what kind of thing it is isn’t what matters.
`nameof` just returns a string representation of the static symbolic name of its operand. `nameof` would be used at runtime (i.e. during code execution), but provides the ability for advanced editors to include it in a “rename” refactoring. The operand merely needs to be an identifier that exists within the current lexical scope. `nameof` would not observe TDZ and would not evaluate any expression. The ECMAScript static semantics would merely: 1) check that the identifier provided to `nameof` is the name of something in the current lexical scope, and 2) replace the expression with a string literal representing the name. If `nameof foo.bar` were allowed `nameof` would not actually evaluate `foo.bar`, but merely result in `”bar”`. `nameof` does not evaluate anything, it is merely a syntactic transformation by the runtime that becomes a string. Ron From: guest271314 <guest271...@gmail.com> Sent: Friday, June 14, 2019 10:07 AM To: Ron Buckton <ron.buck...@microsoft.com> Cc: es-discuss@mozilla.org Subject: Re: Re: What do you think about a C# 6 like nameof() expression for Not following the module example. Would not ```ns``` be an instance of ```Module``` where ```* as ns``` is used? For the ```class``` example would ```nameof``` be equivalent to ```Object.getOwnPropertyDescriptors(other).name.value```? It's not that a language like TypeScript would need this, but rather that users of an editor like VS Code or WebStorm that have a JavaScript language service would benefit from it. Is the primary use case a non-simple text editor; e.g., _not_ gedit (GUI) or pico or nano (CLI), where the user is depending on the program for diagnostics (logging and errors) within a text editor _before_ actually running the code in a given environment - not to log errors during code execution? On Fri, Jun 14, 2019 at 4:29 PM Ron Buckton <ron.buck...@microsoft.com<mailto:ron.buck...@microsoft.com>> wrote: The 'nameof' operator provides the string name of a static symbol (in compiler/linker terms, not an ECMAScript 'Symbol'). This is often useful for diagnostics (logging and errors), and gives developers a way to reduce repetition. It is also extremely helpful in editors that support symbolic "rename" refactoring. While ES functions have a 'name' property, one of the main use cases is to get a string representation of the name of a thing that isn't itself reified as an object, such as a variable, parameter, or module namespace: ``` import * as ns from "foo"; nameof ns; // "ns" let fn = function g() {}; fn.name<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Ffn.name&data=02%7C01%7CRon.Buckton%40microsoft.com%7C104ffaa78f6847e3a31708d6f0eab6e3%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636961288212685352&sdata=sBP1RXbppYfrzbSFUaC%2F80IBZk1tUDqdxeVmbuTveSE%3D&reserved=0>; // "g" nameof fn; // "fn" ``` Here is an example of two common use cases: ``` class C { compare(other) { if (!(other instanceof C)) { throw new TypeError(`Invalid argument: ${nameof other} `); } set prop(value) { this._prop = value; this.emit("propertychanged", nameof prop); } } ``` It's not that a language like TypeScript would need this, but rather that users of an editor like VS Code or WebStorm that have a JavaScript language service would benefit from it. Ron ________________________________ From: es-discuss <es-discuss-boun...@mozilla.org<mailto:es-discuss-boun...@mozilla.org>> on behalf of guest271314 <guest271...@gmail.com<mailto:guest271...@gmail.com>> Sent: Friday, June 14, 2019 9:05:55 AM To: Stas Berkov Cc: es-discuss@mozilla.org<mailto:es-discuss@mozilla.org> Subject: Re: Re: What do you think about a C# 6 like nameof() expression for Have not tried TypeScript. What are the use cases for JavaScript where TypeScript is not used? Does ```nameof()``` check if an object has a specific property name defined (```"MutationObserver" in window```; ```window.MutationObserver```; ```"document" in globalThis```)? On Fri, Jun 14, 2019 at 1:05 PM Stas Berkov <stas.ber...@gmail.com<mailto:stas.ber...@gmail.com>> wrote: Can we revisit this issue? In C# there is `nameof`, in Swift you can do the same by calling ``` let keyPath = \Person.mother.firstName NSPredicate(format: "%K == %@", keyPath, "Andrew") ``` Let's introduce `nameof` in ES, please. Devs from TypeScript don't want to introduce this feature in TypeScript unless it is available in ES ( https://github.com/microsoft/TypeScript/issues/1579 ) This feature is eagarly being asked by TypeScript community. I understand there are couple issues related to `nameof` feature in ES. They are: minification and what to do if user already has `nameof` function. Minification. 1. If your code to be minimized be prepared that variable names will also change. 2. (just a possibility) Minimizer can have option to replace `nameof(someVar)` with result of `nameof` function. What if user already has `nameof` function. 1. To maintain status quo we can user `nameof` function having priority over newly introduced language feature. 2. OR we can use `typeof` syntax, e.g. `nameof msg.userName` (// returns "userName" string) _______________________________________________ es-discuss mailing list es-discuss@mozilla.org<mailto:es-discuss@mozilla.org> https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
