dart中隐式转换运算符的语法是什么？ [英] What is the syntax for implicit cast operator in dart?

问题描述

我想将我的自定义类A的实例转换为int。隐式转换运算符的语法是什么？ （我想我记得有这样的功能，但我不能在网上找到它）

I would like to cast instances of my custom class A to int. What is the syntax of the implicit cast operator? (I thought I remembered that there is such a feature but I can't find it on the web)

int a = (new A());

推荐答案

类型注释不允许影响Dart中的行为。如果您没有在已选中模式下运行，请执行以下操作：

Type annotations are not allowed to affect behavior in Dart. If you're not running in checked mode, then this:

int a = new A();

的工作方式与此相同：

var a = new A();

。换句话说，当不处于检查模式时，欢迎您将 A 存储在注释为 int

at run-time. In other words, when not in checked mode, you're welcome to store your A in a variable annotated as an int, but no actual conversion takes place.

如果您在检查模式下运行，第一个表单将给您一个运行时异常。

If you are running in checked mode, the first form will give you a runtime exception.

我不确定，但我认为你要求的是一种方法来定义你的类之间的转换 A 和 int ，当转换到 int 时会自动发生。没有这样的事情存在，据我所知。你应该简单地定义一个方法来这样做。例如：

I'm not sure, but I think what you're asking for is a way to define a conversion between your class A and int that will happen automatically when "cast" to an int. No such thing exists, to my knowledge. You should simply define a method to do so. For example:

int a = new A().to_i();

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