I am curious about how this going. Did you observe any breakage? I will probably look into at least adding a warning for this in Firefox very soon.
-Tom On Sun, Sep 28, 2014 at 10:09 PM, Oliver Hunt <[email protected]> wrote: > As MarkM said it break on recursion, but we’re also only killing > function.arguments, not (alas) function.caller so you can still build > “pseudo” stack traces. > > Note that neither .arguments nor .caller work in strict mode functions > (they’re specified to throw), and all engines build real stack traces on > exceptions nowadays, so presumably you could have > function getStackTrace() { > try { > throw new Error > } catch (e) { > return e.stackTrace; // or whatever it is > } > } > > —Oliver > > On Sep 28, 2014, at 9:23 AM, Alex Kocharin <[email protected]> wrote: > > > Yes, it's a powerful meta-programming tool. I don't use it much, but it's > sad to see things like that going away from javascript. > > For example, it could allow to build stack traces without any support from > the engine. How do you like this one?: > > ```js > function type(n) { return typeof n } > > function show_trace() { > var me = arguments.callee > > for (var i=0; i<10; i++) { > console.log((me.name || '<anonymous>') > + ' (' + [].slice.call(me.arguments).map(type) + ')') > me = me.caller > } > } > > function foo() { > show_trace() > } > > function bar() { > foo(1, 2, 3) > } > > bar('some string') > ``` > > ``` > $ node test.js > show_trace () > foo (number,number,number) > bar (string) > <anonymous> (object,function,object,string,string) > <anonymous> (string,string) > <anonymous> (object,string) > <anonymous> (string) > <anonymous> (string,object,boolean) > <anonymous> () > startup () > ``` > > > 28.09.2014, 13:59, "Axel Rauschmayer" <[email protected]>: > > Out of historical curiosity: was `Function.arguments` ever useful for > anything? Why not simply use `arguments`? > > On Sep 28, 2014, at 6:51 , John Lenz <[email protected]> wrote: > > I took a look at Google's internal code index for reference to > Function.prototype.arguments and turned up many references to it > (PhpMyAdmin, some Intel benchmark, some internal code, etc). This is only > code used internally at Google (or was at one time) and not by any means > an index of the entire web, but it does use the Closure Compiler and type > information to accurately find references. These are not just simply > references to an "arguments" property but are references to the "arguments" > property off of objects know to be functions. These references roughly > (from my quick perusal), were about 50% were V8 or similar unit tests, 25% > references that could be trivially replaced with a reference to the active > function's "arguments" variable, and 25% were doing something tricky > (Function.caller.arguments, someevent.handler.arguments). > > I'm sure you didn't expect that there would be zero breakage, but I wanted > to give you a heads up that there might be more than you expect. > > > > On Sat, Sep 27, 2014 at 11:38 AM, Oliver Hunt <[email protected]> wrote: > > Hi all, as a heads up we’re going to be doing an experiment in our tree to > see if we can kill off the function.arguments property entirely. > > We’re super hopeful we can make it go away safely, and we’ll post a follow > up when we have some actual information about what happens. > > If you’re interested in following directly you can track the bug: > http://webkit.org/b/137167 > > —Oliver > > > -- > Dr. Axel Rauschmayer > [email protected] > rauschma.de > > > , > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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