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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