This issue is derived from Esprima issue 81 http://code.google.com/p/esprima/issues/detail?id=81
Hello everyone, According to the ECMA262 5.1th, [[Call]] of host object may return Reference Type. So, all values using raw [[Call]] result may be Reference Type. For example, [[Get]] may return Reference Type if *getter* is a host object that [[Call]] returns Reference Type. http://ecma-international.org/ecma-262/5.1/#sec-8.12.3 As the result, GetValue may return Reference Type because that use result value of [[Get]] http://ecma-international.org/ecma-262/5.1/#sec-8.7.1 And, for example, if we define getter of object, getter function is host object that [[Call]] return Reference Type, (10, obj.getter) returns Reference type, so, (10, obj.getter) = 10; is valid because GetValue is performed, but GetValue result is also Reference Type. In the ECMA262 5.1th, GetValue is assumed that doesn't return Reference Type, for exmaple, var obj = { get v() { // this v function is host object and returns Reference; // we can define this v using host object and defineProperty return Reference; } }; And, typeof obj.v Then, typeof should treat Reference Type also, but in 11.4.3, Reference Type is not considered. http://ecma-international.org/ecma-262/5.1/#sec-11.4.3 I think this is a bug of spec and GetValue and [[Get]] should not return Reference type, is it right? To fix this, I think following 3 way are good. 1. perform GetValue on [[Call]] result in the spec 2. re-define [[Get]] and GetValue can return Reference Type. This needs to re-define all the spec part using [[Get]], GetValue and others 3. remove feature that [[Call]] can return Reference Type Because all modern engines don't consider that [[Call]] result is Reference and this feature makes big performance-regression, personally I think 3 is better. Regards, Yusuke Suzuki
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
