Re: Dynamic class default (was Re: Class method addition...)
On Apr 6, 2008, at 8:10 PM, Kris Zyp wrote: Since you grant use-cases for sealing objects against mutation, are you simply arguing about what the default should be (that 'dynamic class' should not be required to get an extensible-instance factory, that 'class' should do that)? Well if it is up for debate... Can we have classes be dynamic by default, and non-dynamic if the class is declared to be final? 'final' already means can't be overridden for methods and can't be extended by subclassing for classes in several languages. Adding another meaning, even if it's of the same mood, seems like a bad idea to me. What's the point of your request? If you mean to promote AOP (a sacred cow, per my last message to you, reply-less :-P), you risk degrading overall integrity, or merely imposing a syntax tax as most class users have to say inextensible class (kidding, but it would have some contextual keyword in front -- and not static). The default should match the common case as decided by programmers using classes because they want greater integrity than they get with closures. Even if a class's instances are extensible, it doesn't mean the fixed properties (fixtures) can be AOP'ed. It just means certain objects can be dressed up to resemble others, by some like relation -- for good or ill. /be ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: Dynamic class default (was Re: Class method addition...)
'final' already means can't be overridden for methods and can't be extended by subclassing for classes in several languages. Adding another meaning, even if it's of the same mood, seems like a bad idea to me. What's the point of your request? If you mean to promote AOP I don't know what the connection would be. (a sacred cow, per my last message to you, reply-less :-P) I ran out of arguments :). , you risk degrading overall integrity, or merely imposing a syntax tax as most class users have to say inextensible class (kidding, but it would have some contextual keyword in front -- and not static). Just a idea for budget cuts, it's rejection doesn't bother me, not an important issue to me. Kris ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: Dynamic class default (was Re: Class method addition...)
Making classes dynamic by default is likely to make the verifier -- what we previously called strict mode -- less effective, because a reference o.x cannot be flagged as an error unless o is known to be an instance of a sealed class that doesn't have an 'x'; if classes are sealed by default then more errors will likely be caught early. Dynamic classes also incur nontrivial overhead in memory use and runtime performance. IMHO we'd want a fairly compelling argument for making all classes dynamic by default. ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: Dynamic class default (was Re: Class method addition...)
On Apr 7, 2008, at 10:37 AM, Steven Johnson wrote: Dynamic classes also incur nontrivial overhead in memory use and runtime performance. IMHO we'd want a fairly compelling argument for making all classes dynamic by default. It would probably put an end to the acrimony about ES4 being too different from ES3; I'm hesitant to speak for the views of others, but I suspect this change would make the language a lot more palatable for many currently opposed to it. In that light, compelling is going to be a highly subjective measurement. ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: Dynamic class default (was Re: Class method addition...)
It would probably put an end to the acrimony about ES4 being too different from ES3; I'm hesitant to speak for the views of others, but I suspect this change would make the language a lot more palatable for many currently opposed to it. In that light, compelling is going to be a highly subjective measurement. Since ES3 doesn't have true classes at all I'm not sure I entirely agree, but I get your point in terms of the feel of the language. Granted, putting an end to acrimony is a Good Thing and not to be ignored, but somehow I don't see any magic bullet that possibly achieve that on its own :-) Let me put it another way: aside from changing the perceived feel of the language, what specific use cases would be made better, faster, more secure, more extensible, more reliable, etc. by such a change? ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
RE: Dynamic class default (was Re: Class method addition...)
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Lars Hansen Sent: 7. april 2008 10:25 ... Kris is suggesting that classes should not be dynamic by default ... Of course what Kris is suggesting that classes *should* be dynamic by default. The 'not' is misplaced, just ignore it. --lars ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: Dynamic class default (was Re: Class method addition...)
On Mon, Apr 7, 2008 at 10:45 AM, Neil Mix [EMAIL PROTECTED] wrote: On Apr 7, 2008, at 10:37 AM, Steven Johnson wrote: Dynamic classes also incur nontrivial overhead in memory use and runtime performance. IMHO we'd want a fairly compelling argument for making all classes dynamic by default. It would probably put an end to the acrimony about ES4 being too different from ES3; I'm hesitant to speak for the views of others, but I suspect this change would make the language a lot more palatable for many currently opposed to it. In that light, compelling is going to be a highly subjective measurement. Speaking as one of the more vocal skeptics, this change would make ES4 less palatable for me. ES3.1 and ES4 are together moving in a good direction by making the degree of permissiveness controllable on a per-property and per-object basis. Subjectively, as someone interested in robustness, integrity, and security, ES3 made a huge mistake in having all these be as permissive as possible. Both ES3.1 and ES4, in order to be reasonably compatible with ES3+R, must continue to have the ES3 constructs default to overly permissive. For ES3.1 the best we can do is provide explicit operations (such as __defineProperty__) for overriding these defaults. To my mind, the main virtue of introducing a class syntax to an ES is an opportunity to get these defaults right this time. One principle of security engineering is deny by default is better than allow by default; which is closely related to whitelisting is better than blacklisting. For ES3.1, we're stuck with allow-by-default. If the ES4 class syntax were to get this wrong as well, I'd be even more puzzled about what its purpose is. Accordingly, my preference is for classes to default to non-dynamic and non-subclassable. For methods to default to non-overridable and non-enumerable. And for properties/members to default to non-settable and non-enumerable. Whatever these defaults are, it's an orthogonal question whether classes need to be a primitive construct, or whether they should be just sugar for a less-permissive-by-default usage of the class-like abstraction pattern of ES3.1. -- Cheers, --MarkM ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: ES4 draft: Object initializers
var (outside of eval, an ES1 flaw) means DontDelete. /be On Apr 7, 2008, at 1:50 PM, Mark S. Miller wrote: On Mon, Apr 7, 2008 at 10:21 AM, Lars Hansen [EMAIL PROTECTED] wrote: IMO it ought to be possible to use 'var' in those same ways but we didn't discuss that much (if at all). I don't understand. What would it mean? -- Cheers, --MarkM ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
Re: ES4 draft: Object initializers
On Mon, Apr 7, 2008 at 2:47 PM, Brendan Eich [EMAIL PROTECTED] wrote: var (outside of eval, an ES1 flaw) means DontDelete. Excellent! -- Cheers, --MarkM ___ Es4-discuss mailing list Es4-discuss@mozilla.org https://mail.mozilla.org/listinfo/es4-discuss
