在异步返回类型 [英] On async return type

问题描述

想知道为什么我们应该指定async方法确实返回Task对象.

Wondering why we should specify that async method does return Task object.

使用async关键字指定它似乎多余，而且由于您并未真正创建Task对象，因此很混乱.

Specifying it seems redundant with the async keyword plus it is confusion since you do not really create the Task object.

据我了解，编译器确实会发出创建Task对象所需的代码(无论是在等待调用中还是用新Task包装返回的内容.)

As I understand the compiler does emit the necessary code for Task object creation (Whether on a await call or wrapping the return with a new Task.).

我真的不喜欢声明类型和返回类型之间的不一致.

I don't really like the inconsistency between the declare type and the return Type.

推荐答案

我有已考虑，但他们决定不这样做.

I have a blog post that describes the reasoning in detail. Inferring the return type was considered but they decided not to.

对于显式返回类型，async关键字更多地是实现细节.具有显式返回类型的原因有两个:

With the explicit return type, the async keyword is more of an implementation detail. There are two reasons to have the explicit return type:

• 方法签名是一致的(声明时与使用IntelliSense或反射观察时是相同的).
• async void和async Task之间存在差异.对于推断的返回类型，没有明确的方法来定义async void方法.

• The method signature is consistent (it's the same at the point of declaration as when observed using IntelliSense or reflection).
• There is a difference between async void and async Task. With an inferred return type, there's no clear way to define an async void method.

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