streamController.add（）和streamController.sink.add（）有什么区别？ [英] What is the difference between streamController.add() and streamController.sink.add()?

问题描述

我知道有两种方法可以将数据添加到streamcontroller中，一种是直接添加，另一种是通过使用接收器添加。我尝试阅读Sink的文档，但无法理解其概念，例如数据管道等。

There are two ways that i know to add data to streamcontroller, one directly and other by use of a sink. I tried to read docs of Sink but i am not able to understand its concept like piping of data etc.

推荐答案

没什么。这在内部做同样的事情。

Nothing. This does the same thing internally.

.sink 属性的真正目的是将其作为其他对象的参数传递。例如：

The real purpose of .sink property is to pass it as parameter of other object. Such as :

MyClass(
  sink: myController.sink,
)

这可防止类访问他们不应该访问的属性。

This prevents classes to access to properties they shouldn't be able to.

但是 StreamController 实现了 Sink ，这有什么意义？

But StreamController implements Sink so what's the point ?

是的。但是将 StreamController 转换为 Sink 不同于创建 Sink 。

Well true. But casting StreamController to Sink is different than creating a Sink.

例如，使用 Sink 的类可以很好地执行以下操作：

For example, the class that uses Sink could very well do the following :

StreamSink sink = StreamController();
if (sink is StreamController) { // this is true
    // access StreamController custom methods
}

此处的接收器字段可以防止这种情况。转换为以下内容：

The sink field is here to prevent this. It translates into the following :

StreamSink sink = StreamController().sink;
if (sink is StreamController) { // false this time
   // never reached
}

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