On Mon, Jun 22, 2009 at 11:07 PM, Maciej Stachowiak<m...@apple.com> wrote: > I suspect most JS bindings in WebKit use the original more complicated > pattern Drew cited, instead of the more succinct but incorrect one.
There are some bugs on file about this. I've been meaning to go through and look at all these cases. >> Here's how the two bindings relate (if you look at both bindings and >> wonder): >> >> v8::Context::GetEntered() ~~ exec->dynamicGlobalObject() >> v8::Context::GetCalling() ~~ exec->lexicalGlobalObject() >> v8::Context::GetCurrent() ~~ ???? >> >> It might be good to add a similar "GetCurrent" concept to JSC >> (although, hopefully with a better name) so we can remove all this >> manual, error-prone caching / mark()ing. > > What does the "current" context correspond to? It's the context in which the method was defined. For DOM methods, V8 treats them as being defined by the context of their owner document. > How is it retrieved? No idea. I think what happens is you enter the context for a particular frame before constructing all the objects / methods for that frame. Then the DOM methods just have a scope like regular JavaScript methods. > Guessing > wildly based on the names, I'm assuming host functions in v8 have the > equivalent of their own scope chain and thus in some sense their own lexical > global object. I'm not an expert on this, but this fits my mental model. In general, V8 tries to implement DOM objects as close to how user-defined objects would be implemented as possible. > We could do that for JSC, except that for most things it > would be useless - it's only potentially useful for DOM-level explicit > constructors, since JS-level ones are supposed to use the calling function's > lexical global object as the basis for everything, and most other host > functions don't need it at all. That's possible. I don't have a good idea of what it costs to provide. The benefit is it makes it easier to write correct bindings code. (Or maybe it makes it harder because you have more contexts to choose from and choosing the right context is subtle.) I don't really know how to solve this problem except by writing tests. However, tests don't really help when introducing new kinds of objects (e.g., workers, database transactions). Adam _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
