为什么在 AppleScript 中不能声明对处理程序本地变量的引用? [英] Why, in AppleScript, can't you declare references to variables local to handlers?

问题描述

为什么不能声明和使用对变量的引用，除非所引用的变量是全局范围的?请解释导致以下现象的运行时内存或对象结构:

Why can't you declare and use references to variables unless the variable referenced is scoped globally? Please explain the runtime memory or object structure that leads to the following phenomenon:

脚本 A 失败:

on foo()        
    set l to {0}
    set lref to a reference to l
    return item 1 of lref
end foo

foo()

脚本 B 成功:

on run
    set l to {0}
    set lref to a reference to l
    return item 1 of lref
end run

脚本 C 成功:

on foo()        
    global l
    set l to {0}
    set lref to a reference to l
    return item 1 of lref
end foo

foo()

另见:您如何在 AppleScript 的处理程序中有效地构建列表? 和 为什么AppleScript不能在这个测试代码中将哈希的firstValue变成类型引用?

推荐答案

因为引用"与对象说明符是一回事，所以你不能引用不包含(或包含在就 AppleScript 而言，它不是)一个对象.

Because a "reference" is the same thing as an object specifier, so you can’t make a reference to something that isn’t (or is contained by something that isn’t) an object as far as AppleScript is concerned.

全局变量归顶级脚本对象所有——它实际上是一个没有初始化器的属性.(您也可以引用脚本属性；它不必是严格的全局属性.)

A global variable is owned by the top-level script object -- it’s really a property with no initializer. (You can also have a reference to a script property; it doesn’t have to be strictly global.)

另一方面，局部变量由它所在的处理程序的调用框架拥有，并且调用框架在 AppleScript 中不是对象，因此没有引用.

A local variable, on the other hand, is owned by the call frame of the handler that it’s in, and call frames are not objects in AppleScript, therefore, no references.

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