On Tue, Dec 4, 2012 at 3:50 PM, Brendan Eich <bren...@mozilla.org> wrote:
> The survey I'd like to see is among underscore, jQuery, and other popular > libraries (go by NPM dependency frequency and client-side use frequency), > how do set-like methods work: return-this or return-v? > > underscore and jQuery side with 1. returning the calling object 2. returning a new object of the same "kind", but with the results of the operation. jQuery objects themselves are similar to a set, most operations on the set itself result in returning a new jQuery object (set) that reflects the results of the operation. As I explained previously, the reason it returns a new jQuery object is to support the end() and addBack() methods by storing the original as a property of the current, this that allows either restoring the original set to it's pre-operation state or adding the original set to the current set. If this were not an API that we supported, jQuery could just as easily be a custom wrapper over an ES6 Set. underscore actually has a special method called _.chain() that returns a wrapped object that allows for chaining all of the underscore APIs—until value() is called, which closely matches the examples I gave yesterday. underscore has a _.defaults() function that returns the mutated object after applying a default set of properties and values (similar to _.extend()). There is no analogous Set api in underscore. for npm in order of most dependencies: 1. underscore (see above). 2. request. - Any API that "sets" something, returns this ( https://github.com/mikeal/request/blob/master/main.js#L735-L758 ) - There is a lib that Mikeal also wrote "form-data" that has an append method that does _not_ return this 3. async. Nothing comparable 4. express. - app.set, and subsequently all aliases, returns this ( https://github.com/visionmedia/express/blob/master/lib/application.js#L250-L261 ) - response.set, and subsequently all aliases, returns this ( https://github.com/visionmedia/express/blob/master/lib/response.js#L37-L40 ) 5. optimist. - every operation that is not a "get" returns self as this; ( https://github.com/substack/node-optimist/blob/master/index.js) 6. commander. - nearly every operation that is not a "get" returns this; ( https://github.com/visionmedia/commander.js/blob/master/index.js) 7. colors - setTheme returns the theme that was set 8. uglify. Nothing comparable 9. connect. - Too much to review, but it's primary API that "sets" values, returns this (see examples in readme) 10. socket.io - Too much to review, nearly everything returns this ( https://github.com/LearnBoost/socket.io/blob/master/lib/socket.js) When I was researching whether or not it was worthwhile to pursue this discussion, I reviewed most of this stuff, as well as web-focused libs. At the moment I have to head out, so I can't continue to research this, but I'll gladly spend as many hours as anyone thinks is necessary to prove my position. Rick > This is closer than a people-survey to mapping the cowpath. > > /be >
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