On Dec 21, 2010, at 2:12 PM, Brendan Eich wrote: > I also see the ocap purity of soft fields, and I like Mark's > AST-decorated-sparsely soft fields use-case. But we already have weak maps in > harmony:proposals, so one can write such code now, just at some loss of > convenience: without square brackets or (even better) dots for convenient > soft-field access expressions.
(I'm not sure where Mark's original AST use case is, or I would have also quoted it.) To me, this use case sounds like a form of aspect oriented programming. I'm not at all sure that AOP support is something we want to add as an additional requirement to our designs. As Brendan points out, if you really want to do this, you can use weak maps whose inclusion I strongly support for exactly this sort of use case. However, why would you bother freezing your AST nodes in the first place. JavaScript has a great mechanism for "soft fields" -- it's called properties. You can even make your base properties non-configurable if you want to. But why make them non-extensible in this situation. My sense that this is a great fear of an important segment of the JavaScript usage community. That people will start arbitrarily freezing or otherwise locking down objects resulting in systems that are much less "elastic" then they are today. Allen _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
