Ecmascript函数的真实世界示例返回Reference？ [英] Real world examples of Ecmascript functions returning a Reference?

问题描述

阅读 EcmaScript规范，第8.7节参考规范类型 ：

参考类型用于解释此类运算符的行为as delete ， typeof ，以及赋值运算符。 [...]引用是已解析的名称绑定。

The Reference type is used to explain the behaviour of such operators as delete, typeof, and the assignment operators. […] A Reference is a resolved name binding.

允许函数调用返回引用。纯粹为了宿主对象而承认这种可能性。此规范定义的内置ECMAScript函数没有返回引用，并且没有为用户定义的函数提供返回引用。

Function calls are permitted to return references. This possibility is admitted purely for the sake of host objects. No built-in ECMAScript function defined by this specification returns a reference and there is no provision for a user-defined function to return a reference.

最后两句话让我印象深刻。有了这个，你可以做一些事情，比如 coolHostFn（）= value （有效的语法，顺便说一句。所以我的问题是：

Those last two sentences impressed me. With this, you could do things like coolHostFn() = value (valid syntax, btw). So my question is:

是否有任何EcmaScript实现定义了导致 Reference 值的主机函数对象？ / p>

Are there any EcmaScript implementations that define host function objects which result in Reference values?

推荐答案

谷歌Chrome的引擎非常有效。但是，你会注意到在控制台中你会得到一个 ReferenceError：在执行以下内容时，在赋值中的左侧无效：

Google Chrome's engine works very much in this way. However, you'll notice in the console you'll get an ReferenceError: Invalid left-hand side in assignment when executing the following:

var myObj = new Object();
function myFunc() {
    myObj.test = "blah";
    return myObj;
}
myFunc() = new String("foobar");

然而，这是一个早期错误，因为v8的ECMAScript实现，如果它正确的话应该可行在假设引用错误之前执行 myFunc 。

This is an Early Error, however, and because the v8's ECMAScript implementation, this should work if it properly executes myFunc before assuming the reference error.

那么，在v8的当前实现中？是和否。它默认实现（由于语言的结构），但是功能因不同的问题而停止。 coolHostFn（）= value 不应该返回错误，并且确实应该能够正确执行。但是 3 = 4 应该肯定会返回左侧分配错误。

So, in v8's current implementation? Yes and No. It is implemented by default (due to how the language is structured), however the capability is halted by a different issue. coolHostFn() = value should not return an error, and should indeed be able to execute properly. However 3=4 should most certainly return a left-hand side assignment error.

不完全是你的回答问题，但我希望它有助于澄清为什么它不起作用。

Not exactly an answer to your question, but I hope it helps clarify why it doesn't work.

（以下是问题/票据以防任何人想要加入...... http://code.google.com/p/v8/issues/detail?id=838 ）

(Here's the Issue/Ticket in case anyone wants to chime in... http://code.google.com/p/v8/issues/detail?id=838 )

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