(Sorry for the delay of response, I am currently in a remote area.) Le 7 juil. 2014 à 19:02, Kevin Smith <[email protected]> a écrit :
>> >> 1. During phase /* 1 */, the this-binding is uninitialised; trying to access >> it through an explicit `this` keyword will throw a ReferenceError. > > This seems overly restrictive to me. The common case (as in ES5) will be > classes that derive from Object, where no such restriction is necessary. > (To be more precise, the intended restriction is a TDZ, just like `const` declarations.) There are trade-offs that should be made. Are there many cases where you want to manipulate `this` before calling `super`? > The crux of the problem is that some host-defined classes that cannot safely > separate object allocation from initialization. What if the @@create hook > was allowed to return undefined? In such a case, your "uninitialized" > semantics would apply: attempting to dereference "this" before calling > super(...) would throw an error, and super(...) would essentially set the > "this" value? In all other cases, the currently drafted semantics would > apply. > One feature of the proposal is that the first call to `super` invokes the constructor with the semantics of [[Construct]] rather than [[Call]], so that subclassing classes that have different construct/call behaviour would just work. It implies that there is no preliminary creation step. —Claude
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