Re: [ClojureScript] Extending protocol to an existing JavaScript type

Hmm I think you have those confused. Take the equivalent from Java: class MyClass { } MyClass x = new MyClass(); Class y = MyClass.class; or JS: var MyClass = function() { /* ctor */ }; var inst = new MyClass() inst != MyClass inst.prototype == MyClass inst is an instance of MyClass

Re: [ClojureScript] Extending protocol to an existing JavaScript type

<< Your code has this in it: Object.prototype.toString.call(this) which is something you usually do not do. The first argument to the .call function becomes "this" in the context of the function which is "cheating" and bypassing prototype inheritance. I consider .call equal to reflection in

Re: [ClojureScript] Extending protocol to an existing JavaScript type

<< var MyClass = function() { /* ctor */ }; var inst = new MyClass() inst.prototype == MyClass >> "inst is an instance of MyClass (prototype) but not equal to MyClass." Yes, no one argues with that. It is an instance of MyClass and it is obviously !== MyClass, But saying 'inst.prototype ==

Re: [ClojureScript] Extending protocol to an existing JavaScript type

Crossed context here. What I was pointing to is that trying to create an instance without "new" means that 'this' in the prototype method whatAmI will point to the prototype itself rather than the instance. That is what the === proves in the example in my previous rely. I thought it was the

Re: [ClojureScript] Extending protocol to an existing JavaScript type

For a little JavaScript WTF and one reason why things are the way the are: Number.prototype.whatAmI = function() { return typeof(this); }; var x = 1; x.whatAmI(); "object" typeof(x) "number" Fun times debugging that ... Cheers, /thomas -- Note that posts from new members are moderated -

Re: [ClojureScript] Extending protocol to an existing JavaScript type

> The point I wanted to make is 'this' without 'new' will refer to the object > the function is defined on be it 'window' or whatever object. > That is incorrect. "this" is the actual number, not window. new or not. Behavior is probably different for other types. ;) Number.prototype.addFive

Re: [ClojureScript] Extending protocol to an existing JavaScript type

:) Indeed ... different than the usual way, see below for how "new" changes 'this' from being the object whatAmI is defined on to var T = function() { console.log('constructor called')} T.prototype = {} T.prototype.whatAmI = function() { return {type: Object.prototype.toString.call(this),

Re: [ClojureScript] Extending protocol to an existing JavaScript type

thomas, << Number.prototype.whatAmI = function() { return typeof(this); }; var x = 1; x.whatAmI(); "object" typeof(x) "number" >> var x = 1 is the same as ... var x = Number(1) So in both cases x.whatAmI is going to refer to Number.prototype which is indeed of type [object Number] or as

Re: [ClojureScript] Extending protocol to an existing JavaScript type

On Friday, 4 September 2015 20:42:46 UTC+3, Scott Nelson wrote: > OK, thanks. Great documentation by the way. Definitely going to refer to > this from now on. Francis, Do you have an ide yhy the implementation of `extend-type` for: 1. js types modifies the js type itself 2. while for cljs

Re: [ClojureScript] Extending protocol to an existing JavaScript type

It's not safe to change the JavaScript base types directly - besides the obvious down sides of global changes to types you don't control, this often triggers dramatic de-optimization in JavaScript engines. David On Sun, Sep 6, 2015 at 12:27 PM, Shaun LeBron wrote: > I

Re: [ClojureScript] Extending protocol to an existing JavaScript type

I just looked at the implementation, and it's not done 'from the outside' for cljs types. `extend-type` adds protocol methods to the type object's prototype. Only exception is for JS base types (e.g. "function", "number", "array"). You can see the effects in this gist:

Re: [ClojureScript] Extending protocol to an existing JavaScript type

OK, thanks. Great documentation by the way. Definitely going to refer to this from now on. -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group. To

Re: [ClojureScript] Extending protocol to an existing JavaScript type

Extending a protocol to one of the global JS objects is bad for the same reason it is bad in Javascript: you are modifying a global object. Your extend-protocol is like saying Function.prototype.FOO_foo = function(this, arg){...} in javascript. (The "FOO_foo" is a long namespaced and mangled

Re: [ClojureScript] Extending protocol to an existing JavaScript type

Thanks- that worked perfectly. I did not need to extend IFn and I actually got a runtime error when I tried (perhaps because IFn is a protocol in ClojureScript?). What are "function"/"object"/ect. in this case, syntactically? Is there any documentation about this? Thanks again! -Scott --

Re: [ClojureScript] Extending protocol to an existing JavaScript type

(defprotocol Foo (foo [arg])) (extend-protocol Foo js/Function (foo [arg] (println arg))) -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group.

Re: [ClojureScript] Extending protocol to an existing JavaScript type

Coukd you please post the code that produces that warning? Ideally a minimal case. On Thursday, 3 September 2015, Scott Nelson wrote: > Why is this bad practice? I'm trying to extend a protocol to js/Function > and I get the following warning: > > WARNING: Extending an