On Wed, Dec 9, 2009 at 6:28 AM, Oliver Hunt <[email protected]> wrote: > > On Dec 8, 2009, at 2:18 AM, David-Sarah Hopwood wrote: > >> Oliver Hunt wrote:
> I have also yet to see an actual developer centric use case -- the most > frequently repeated use cases seem to be analysis tools used to ensure code > can be run on a standard ES implementation while essentially being a stricter > subset of ES. The developer scenario for that is "developer wishes to use > 'safe' subset of ES", not "developer wants to perform their own analysis" > > --Oliver Run time mashups? As a developer, I now have access in some browsers to a cross domain enabled getJSON method. Suppose I wanted to use that to retrieve a javascript program from another server (perhaps some kind of module repository), but since I don't trust external code, I want to validate it before I compile it to a JS function, or run it. This is, as you say, a code analysis task. However, in this case, the developer wants to ensure that someone else is using a safe subset of js, rather than as you put it, the developer simply wanting to ensure their own code is in the safe subset. Right now there are projects to do this (caja, adsafe), but to do a runtime check requires that the user download a full JS parser, and validator. If part of the parsing task was built into the browser, there would be less code to download, and the verification would run much faster. This has real implications for users and developers, and would enable new and novel uses for JS in a browser, and distributed code modules. Perhaps most of this is possible with just a hermetic eval, or some kind of worker inspired api as crockford suggested once, however consider this: There is a nice function in js called map which takes a function. If that function could be guaranteed to have certain properties (such as being referentially transparent), then map could be safely broken up into parts and run in parallel, with perhaps a worker api implementation. You could do that now, but it requires some degree of faith that the provided function doesn't do anything naughty. You would not be able to accept such a function from a user, or from an external server. Anyway, I'm sure there's other uses. Just a thought. _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
