无法在咖啡脚本中声明命名函数

Question

如果我想通过constructor.name 获取函数的名称。

例如，在js中我们可以这样做：

var Foo = function Foo() {
    // I need other public methods can also access this private property.
    var non_static_private_member = 10;

    this.a_public_method = function() {
        non_static_private_member = 1;
    }

    console.log(non_static_private_member++);
}
var a = new Foo(); // output >> "10"
var b = new Foo(); // output >> "10"

console.log(a.constructor.name); // output >> "Foo"

但是在咖啡中b = new Foo 不能输出10，它输出11：

class Foo
   non_static_private_member = 10
   constructor: ->
       console.log(non_static_private_member++)

a = new Foo  # output >> "10"
b = new Foo  # output >> "11"
console.log a.constructor.name # output >> "Foo"

但是如果我这样声明咖啡，a.constructor.name 的输出是错误的：

Foo = ->
   non_static_private_member = 10
   console.log(non_static_private_member++)

a = new Foo  # output >> "10"
b = new Foo  # output >> "10"
console.log a.constructor.name # output >> ""

上面的js代码怎么翻译成coffee？

Answer 1

上面的js代码怎么翻译成coffee？

您将驻留在构造函数Foo 中的所有代码放在Foo 类的constructor 中：

class Foo
  # what you put here *is* static
  constructor: ->
    # it's an instance member, so it goes into the constructor
    non_static_private_member = 10;

    @a_public_method = ->
      non_static_private_member = 1
      return

    console.log(non_static_private_member++);

a = new Foo(); # output >> "10"
b = new Foo(); # output >> "10"

Answer 2

CoffeeScript 只会在与 class 语法一起使用时生成命名函数。 基本上，您的第一个 sn-p 将转换为

var Foo;
Foo = (function() {
    var non_static_private_member;
    non_static_private_member = 10;
    function Foo() {
        console.log(non_static_private_member++);
    }
return Foo;
})();

第二个会变成

var Foo;
Foo = function() {
    var non_static_private_member;
    non_static_private_member = 10;
    return console.log(non_static_private_member++);
};

This answer 稍微解释了这种代码生成背后的原因。

对于私有字段，可以做一个类似JS的技巧：

class Foo
   constructor: ->
       non_static_private_member = 10
       console.log(non_static_private_member++)
       @some = -> console.log(non_static_private_member)

a = new Foo  # output >> "10"
b = new Foo  # output >> "10"
a.some() # output >> "11"
console.log a.constructor.name # output >> "Foo"