Confirmed users, Bureaucrats and Sysops emeriti
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JSObject Makeover: Difference between revisions
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Spun out from [https://bugzilla.mozilla.org/show_bug.cgi?id=408416]. | |||
== Possible JSObject changes == | == Possible JSObject changes == | ||
* ops belongs on obj, not map | * ops belongs on obj, not map | ||
* shape belongs on obj, not map, for cache-ready object types | * shape belongs on obj, not map, for cache-ready object types | ||
** this makes a many-from-one update problem when regenerating shape | |||
** alternative idea: share scope among all same-shaped objects in a thread | |||
* obj should be something we can easily subclass, as we do with JSFunction | * obj should be something we can easily subclass, as we do with JSFunction | ||
** this may require more size classes in the GC allocator | |||
== Possible JSObjectOps changes == | == Possible JSObjectOps changes == | ||
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Note that the current machinery avoids recursing on the C stack by iterating instead when the prototype _IS_NATIVE. If we plan to wrap and stack freely, we'll want to avoid recursion in a less hackish way, e.g. by designing the ops to do tail calls or by making some ops refer only to "own" properties. | Note that the current machinery avoids recursing on the C stack by iterating instead when the prototype _IS_NATIVE. If we plan to wrap and stack freely, we'll want to avoid recursion in a less hackish way, e.g. by designing the ops to do tail calls or by making some ops refer only to "own" properties. | ||
(The lookup design has to be able to optimize across same-ops proto chains. This is the requirement that results in what may seem hackish but is (as you suggest) really tail call flattening into iteration. You can see where a non-native object along the chain causes js_LookupPropertyWithFlags to vector off into the foreign ops' lookupProperty hook. /be) | |||
== Possible JSAPI changes == | == Possible JSAPI changes == | ||
* Stop exposing JSObjectOps via jsapi.h. | * Stop exposing JSObjectOps via jsapi.h. | ||
** Huzzah! let's do this now. | |||
* Start phasing out JSClass from the API too. Deprecate JSExtendedClass. (Once we have ops for everything, I think we can mostly stop using JSClass internally too. Depends on a few things.) | * Start phasing out JSClass from the API too. Deprecate JSExtendedClass. (Once we have ops for everything, I think we can mostly stop using JSClass internally too. Depends on a few things.) | ||
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* Kill resolve flags, of course. Deprecate JS_LookupPropertyWithFlags. | * Kill resolve flags, of course. Deprecate JS_LookupPropertyWithFlags. | ||
** The DOM requires JSRESOLVE_ASSIGNING and JSRESOLVE_QUALIFIED or equivalents; don't reinvent as round a wheel! | |||