为什么C#接口中不能声明async异步函数（转载）
Unable to declare Interface “ async Task<myObject> MyMethod(Object myObj); ”
问
I'm unable to declare
interface IMyInterface { async Task<myObject> MyMethod(Object myObj); }
The compiler tells me:
- The modifier async isn't valid for this item
- The async modifier can only be used for methods that have a body
Is this something that should be implemented, or does the nature of async & await prohibit this from ever occurring?
答1
Whether a method is implemented using async/await or not is an implementation detail. How the method should behave is a contract detail, which should be specified in the normal way.
Note that if you make the method return a Task or a Task<T>, it's more obvious that it's meant to be asynchronous, and will probably be hard to implement without being asynchronous.
From How to force async child overrides in C# 5.0
答2
Whether or not your implementation is async, has no relevance to your interface. In other words, the interface cannot specify that a given method must be implemented in an asynchronous way.
Just take async out of your interface and it will compile; however, there is no way to enforce asynchronous implementation just by specifying an interface.
