Ok, so there is no ongoing performance penalty if I change the prototype of an object?
Is there a reason there's no API call for setting the prototype of a javascript object created in C++ to a javascript-created object? In other words, why does v8::Object::New() not have an option to take a v8::Object? On Fri, Feb 12, 2016 at 2:41 AM, Jakob Kummerow <[email protected]> wrote: > It avoids having to change the prototype. > > (That warning on MDN is awesome, strong +1 to that. Being able to modify > prototypes at all is a mis-feature IMHO.) > > On Fri, Feb 12, 2016 at 10:47 AM, Zac Hansen <[email protected]> wrote: > >> >> When you say: >> >> > The preferred way to set a newly allocated object's prototype is to >> use the FunctionTemplate's PrototypeTemplate. See the large comment for >> class FunctionTemplate in v8.h. >> >> >> What does "preferred" mean? Is it because of the type of thing in the >> warning I put in my original post? Or some other reason why that method >> is "preferred"? >> >> --Zac >> >> >> On Fri, Feb 12, 2016 at 1:34 AM, Jakob Kummerow <[email protected]> >> wrote: >> >>> Whether an object's prototype is changed from JavaScript or from C++ >>> doesn't make a difference. (Why would it?) >>> >>> The preferred way to set a newly allocated object's prototype is to use >>> the FunctionTemplate's PrototypeTemplate. See the large comment for class >>> FunctionTemplate in v8.h. >>> >>> >>> On Fri, Feb 12, 2016 at 5:44 AM, Zac Hansen <[email protected]> wrote: >>> >>>> I want to do the equivalent of Object.create() in javascript from C++, >>>> but I don't see any way to specify the prototype of a new v8::Object from >>>> the API. >>>> >>>> I was planning on creating the object with v8::Object::New and then >>>> calling v8::Object::SetPrototype() on it, until I saw this: >>>> >>>> >>>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/setPrototypeOf >>>> >>>> Warning: Changing the [[Prototype]] of an object is, by the nature of >>>> how modern JavaScript engines optimize property accesses, a very slow >>>> operation, in *every* browser and JavaScript engine. The effects on >>>> performance of altering inheritance are subtle and far-flung, and are not >>>> limited to simply the time spent in obj.__proto__ = ... statement, but >>>> may extend to *any* code that has access to *any* object whose >>>> [[Prototype]] has been altered. If you care about performance you >>>> should avoid setting the [[Prototype]] of an object. Instead, create a >>>> new object with the desired [[Prototype]] using Object.create() >>>> <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create> >>>> . >>>> >>>> >>>> That's a pretty terrifying situation, so I want to make sure that using >>>> SetPrototype() doesn't incur that kind of penalty - at least on a newly >>>> created and unused object. >>>> >>>> Thank you. >>>> >>>> --Zac >>>> >>>> -- >>>> -- >>>> v8-users mailing list >>>> [email protected] >>>> http://groups.google.com/group/v8-users >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "v8-users" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >>> -- >>> v8-users mailing list >>> [email protected] >>> http://groups.google.com/group/v8-users >>> --- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "v8-users" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/v8-users/L9e3eHyjE4A/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> -- >> v8-users mailing list >> [email protected] >> http://groups.google.com/group/v8-users >> --- >> You received this message because you are subscribed to the Google Groups >> "v8-users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > > -- > -- > v8-users mailing list > [email protected] > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to a topic in the > Google Groups "v8-users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/v8-users/L9e3eHyjE4A/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
