I honestly think that is a new model to explain out there, and for a language many misunderstood already because of the magic `this` behavior ... fat arrow introduces a whole new world of foot-guns and a third option over inheritance and/or mixins.
The fact you need a lot of bind in the DOM suggests me you were not familiar or did not consider the handleEvent approach that really simplifies that a lot. If this is not the case than yes, fat arrow is useful for you. This just to say that I am not saying it won't help, I am trying to understand where it does. Thanks On Wed, Oct 2, 2013 at 3:12 PM, Aymeric Vitte <[email protected]>wrote: > Andrea, it's difficult to understand why you think the fat arrow does not > help or I misunderstood your point, if |this| is already bound to > something, like for events, then you don't need it, if you want to bind to > something else then you use bind, if you want to bind to the outer |this| > then you use the fat arrow, that's extremely usefull, even in a DOM env, > because for example while handling events you probably have the case of > binding |this| again inside, but DOM is not only events, I am using a lot > bind(this) in DOM, node, etc and will replace it as previously mentioned by > the fat arrow when available. > > Regards, > > Aymeric > > Le 02/10/2013 20:11, Andrea Giammarchi a écrit : > > You need to be sure about the `this` because today you can `bind(anyObject > || this)` while with fat arrow you can only bind `this` so you need to be > sure that the function context, the one everybody has always borrowed > through call and apply, is the one you expect to be. > > In a new direction where instanceof is being discouraged, the usage of > this become critical. > > As shortcut, fat arrow fails. `var o = {method: () => whatver;};` > > As DOM listener it brings what `handleEvent` does since ever. > ```javascript > var o = { > init: function () { > document.addEventListener('click', this); > // virtually the same of > document.addEventListener('click', (e) => this.handleEvent(e)); > }, > handleEvent: function () { > this === o; > } > }; > ``` > > So I don't see many advantages on DOM world. > > Once again, I am trying to understand where is the glory of this new > feature. > > I am not saying it should not be there, ES6 classes and generators > already breaks the old syntax so it won't hurt a new utility as fat arrow > is but where this will be exactly a better approach to the current > situation ? > > The only one that comes into my mind is the `once` event listener in > node or eddy.js ... but `once` a part, and I admit in there it's handy, I > cannot see many other real/concrete usages. > > In CoffeeScript the fat arrow behaves differently having a dynamic this, > am I correct? > So whoever is comparing fat arrow with CoffeeScript should be aware these > are completely different beasts and there was my question about what is > solving for the real world. > > No need to talk about use strict. > > Thanks > > > > > > On Wed, Oct 2, 2013 at 11:01 AM, Brendan Eich <[email protected]> wrote: > >> Andrea Giammarchi wrote: >> >>> fat arrow does not add any capabilities but create the need to be sure >>> about the context. >>> >> >> This does not make sense. The problem of being unsure about "which this" >> already exists. Adding arrows does not make it worse. The new syntax makes >> it better, compared to 'var self = this;' or .bind(this) hacks that are >> more verbose and easy to forget -- that is, whose absence is easy to >> overlook. >> >> >> In use strict fat arrow will bring a lovely `undefined` wich is >>> undesired so nothing is solved in there. >>> >> >> Stop comparing apples to oranges. If we have today >> >> "use strict"; >> function foo() { >> ... >> setCallback(function () { ... this ...}.bind(this)); >> } >> >> >> Then you have no greater or lesser incidence of undefined-this bugs due >> to someone calling foo() instead of foo.call, foo.apply, or obj = >> {method:foo}, obj.method() by changing this code to use an arrow: >> >> "use strict"; >> function foo() { >> ... >> setCallback(() => {... this ...}); >> } >> >> >> If you don't like strict mode, keep that out of this thread. Incidence of >> undefined-this bugs due to it do not change with arrows. >> >> /be >> > > > > _______________________________________________ > es-discuss mailing > [email protected]https://mail.mozilla.org/listinfo/es-discuss > > > -- > Peersm : http://www.peersm.com > node-Tor : https://www.github.com/Ayms/node-Tor > GitHub : https://www.github.com/Ayms > >
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