Proxies and function names: properties that are always non-configurable

David Bruant bruant.d at
Fri Apr 13 01:18:11 PDT 2012

Le 13/04/2012 01:36, Brandon Benvie a écrit :
> With Direct Proxies there's no such thing as a fully virtual object. 
> Virtualized objects can be achieved by just creating a new 
> empty/placeholder object with the desired invariants ([[prototype]], 
> [[class]], etc). This is all well and good except it turns a handful 
> of non-internal properties into invariants as well, mostly the 
> properties auto-installed on functions. [arguments, name, caller, 
> length] are non-configurable non-writable, prototype is non-configurable.
I think that fully virtualized objects is not a goal. Conservation of 
invariant is an important property specifically for what you're asking 
If it can be reassuring, I think fat arrow functions (or whatever 
simpler function is created) will not have the properties you 
mentionned, so it'll be possible to wrap them in proxies and have the 
properties you wish for.

> With other objects you can mostly manage the problem by creating a new 
> instance using Object.create since nothing comes preinstalled. This 
> obviously doesn't work for a functions, nor have I seen semantics on 
> how inheritance for functions is support to work once we actually have 
> the ability to do that. Has this been discussed anywhere yet? Have the 
> semantics of how inheritance for functions is supposed to work in 
> regards to the above properties?
Since proxies preserve function invariants, what happens with proxies is 
what should happen with the wrapped function.


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