Module isolation

Brendan Eich brendan at mozilla.com
Mon Jan 18 08:42:38 PST 2010


On Jan 18, 2010, at 4:38 AM, Mark S. Miller wrote:

> Obviously, I will have many positive things to say about the Valija  
> approach for accommodating legacy. In fact, it was invented in order  
> to cope with the "highly popular Prototype library" you mention  
> below. However, the picture is not as rosy as "a burden [only] on  
> implementors". The semantics of computing between Valija contexts  
> are complicated, in similar but different manner to how the  
> semantics of JS across frames is complicated today. If there's  
> interest, I can present Valija with slides 10-15 of <http://ses.json.org/millerses.pdf 
> >.

Perhaps Valija is not the last word on this approach :-/. There's the  
system Adam Barth is developing -- have you checked that out?


>
> * The highly popular Prototype library, and a lot of extant code,  
> modifying primordials. If all such code must be rewritten to work in/ 
> with modules, then modules have a steep adoption hill to climb.
>
>
> I don't quite understand this. Prototype does not currently work  
> with modules, so some rewrite is necessary in any case. As long as  
> we're talking about future Prototype, my impression is that they  
> wanted to migrate away from mutating primordials eventually anyway.

Tobie et al. may want to, but I know many *users* of Prototype who do  
not. We're talking about a large number of actual uses, some of which  
might want to migrate into a module, not necessarily be used cross- 
module. The cost of doing so is low if primordials in that module can  
be mutated. It goes way up if they can't.

/be

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