[[Class]] and host objects
Allen.Wirfs-Brock at microsoft.com
Tue Feb 10 18:15:22 PST 2009
>Mark Miller: I like your #2 direction a lot. If it were feasible to require that host objects not even use [[Class]] "Object", I'd be in favor. However, I'm guessing that would differ too greatly from current browser behavior to have a chance.
That's what I thought until I probed around a few DOM objects in IE and Firefox and didn't see any [object "Object"]'s. We probably need the browser experts to tells whether or not it is common practice to use [[Class]]=="Object" for host objects but a casual inspection looked promising.
From: Mark S. Miller [mailto:erights at google.com]
Sent: Tuesday, February 10, 2009 6:01 PM
To: Allen Wirfs-Brock
Cc: Mark Miller; Brendan Eich; es-discuss
Subject: Re: [[Class]] and host objects
2009/2/10 Allen Wirfs-Brock <Allen.Wirfs-Brock at microsoft.com<mailto:Allen.Wirfs-Brock at microsoft.com>>
Mark Miller said: We can get the effect of specifying such indistinguishability simply by specifying that host objects may have as their [[Class]] property "Object", or any string not otherwise used by the spec as a [[Class]] value.
I generally agree, but I have two "what about's" that actually go in different directions from each other.
#1 What about "Function" in addition to "Object"? It seems reasonable to have host objects that are functions in addition host objects that are objects. (Counter-argument: slippery slope)
#2 Why allow "Object" for host objects that are required to conform to the section 15.3 specification for Object. If they are distinguishable from section 15.3 objects they should have [[Class]]=="Object". An implementation can use "HostObject" or something else. (Counter-argument: Might confuse some programmers??? (seems weak))
I like your #2 direction a lot. If it were feasible to require that host objects not even use [[Class]] "Object", I'd be in favor. However, I'm guessing that would differ too greatly from current browser behavior to have a chance.
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