Function apply and call (was RE: Bait taken: Arguments about arguments)

Brendan Eich brendan at mozilla.com
Thu Jan 15 22:27:23 PST 2009


On Jan 15, 2009, at 10:18 PM, Mark S. Miller wrote:

> Wonderful! And Brendan, you said earlier you were open to freezing  
> strict arguments, and that the joining of arguments should be  
> severed by freezing.

Yes. This is easy to implement with a few strict mode checks in  
existing arguments implementations I know of. Other implementors  
should give their thoughts, of course.


> With these two changes, virtual-ES-strict-in-ES-strict emulations  
> such as future Valija will be able to easily emulate strict  
> arguments. An emulated strict arguments need only be a normal frozen  
> non-array object inheriting from Array.prototype with appropriate  
> length, caller, callee, and constructor properties. Otherwise, self- 
> virtualizations would have needed to create a genuine arguments  
> object, since the difference would have been observable. I should  
> have mentioned this earlier as another motivation.

That's a good point. Emulating arguments with its magic data  
properties that a mysterious agent (as Allen put it) keeps in sync  
with parameters is Hard(tm).

/be


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