CoffeeScript中的私有成员？
CoffeeScript中的私有成员？
提问于 2011-01-14 05:43:24
有人知道如何在CoffeeScript中创建私有的、非静态的成员吗？目前我正在这样做，它只是使用了一个以下划线开头的公共变量，以澄清它不应该在类的外部使用：
class Thing extends EventEmitter
constructor: (@_name) ->
getName: -> @_name将变量放入类中使其成为静态成员，但如何使其成为非静态成员呢？有没有可能在不“花哨”的情况下？
回答 7
Stack Overflow用户
发布于 2011-12-01 07:12:24
类只是函数，所以它们创建作用域。在这个作用域中定义的所有内容从外部都是不可见的。
class Foo
# this will be our private method. it is invisible
# outside of the current scope
foo = -> "foo"
# this will be our public method.
# note that it is defined with ':' and not '='
# '=' creates a *local* variable
# : adds a property to the class prototype
bar: -> foo()
c = new Foo
# this will return "foo"
c.bar()
# this will crash
c.foocoffeescript将其编译为以下代码：
(function() {
var Foo, c;
Foo = (function() {
var foo;
function Foo() {}
foo = function() {
return "foo";
};
Foo.prototype.bar = function() {
return foo();
};
return Foo;
})();
c = new Foo;
c.bar();
c.foo();
}).call(this);Stack Overflow用户
发布于 2012-09-26 13:54:02
我想展示一些更花哨的东西
class Thing extends EventEmitter
constructor: ( nm) ->
_name = nm
Object.defineProperty @, 'name',
get: ->
_name
set: (val) ->
_name = val
enumerable: true
configurable: true现在你可以做
t = new Thing( 'Dropin')
# members can be accessed like properties with the protection from getter/setter functions!
t.name = 'Dragout'
console.log t.name
# no way to access the private member
console.log t._nameStack Overflow用户
发布于 2014-11-23 21:35:31
这里有一个解决方案，它借鉴了这里的几个其他答案以及https://stackoverflow.com/a/7579956/1484513。它将私有实例(非静态)变量存储在私有类(静态)数组中，并使用对象ID来知道该数组的哪个元素包含属于每个实例的数据。
# Add IDs to classes.
(->
i = 1
Object.defineProperty Object.prototype, "__id", { writable:true }
Object.defineProperty Object.prototype, "_id", { get: -> @__id ?= i++ }
)()
class MyClass
# Private attribute storage.
__ = []
# Private class (static) variables.
_a = null
_b = null
# Public instance attributes.
c: null
# Private functions.
_getA = -> a
# Public methods.
getB: -> _b
getD: -> __[@._id].d
constructor: (a,b,@c,d) ->
_a = a
_b = b
# Private instance attributes.
__[@._id] = {d:d}
# Test
test1 = new MyClass 's', 't', 'u', 'v'
console.log 'test1', test1.getB(), test1.c, test1.getD() # test1 t u v
test2 = new MyClass 'W', 'X', 'Y', 'Z'
console.log 'test2', test2.getB(), test2.c, test2.getD() # test2 X Y Z
console.log 'test1', test1.getB(), test1.c, test1.getD() # test1 X u v
console.log test1.a # undefined
console.log test1._a # undefined
# Test sub-classes.
class AnotherClass extends MyClass
test1 = new AnotherClass 's', 't', 'u', 'v'
console.log 'test1', test1.getB(), test1.c, test1.getD() # test1 t u v
test2 = new AnotherClass 'W', 'X', 'Y', 'Z'
console.log 'test2', test2.getB(), test2.c, test2.getD() # test2 X Y Z
console.log 'test1', test1.getB(), test1.c, test1.getD() # test1 X u v
console.log test1.a # undefined
console.log test1._a # undefined
console.log test1.getA() # fatal error页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/4685626
复制相关文章
相似问题