Not all codepaths return a value error in async statement lambda-CodePudding

I was attempting to wrap a call to a service as a function in order to pass it to a retry framework. I first tried the following:

Func<Task<Obj>> serviceCall = async () => await this.client.call();

Obj callResponse = await retryPolicy.ExecuteAsync(serviceCall);

This code compiles, however, I wanted to write to log for every function call, so I attempted to add the log to the function. My thinking was to change the function to this:

Func<Task<Obj>> serviceCall = async () => {
    logger.log("Calling client");
    await this.client.call();
};

However, now visual studio tells me not all code paths return a value in lambda expression of type Func<Task\<Obj>>. Somehow adding the curly braces, and turning it from an expression lambda to a statement lambda is causing some issue, I assume with the asynchronous part of the code.

CodePudding user response：

You are declaring Func<Task<Obj>> which takes no parameters and returns a Task<Obj>

When you use the expression syntax like this:

Func<Task<Obj>> serviceCall = async () => await this.client.call();

It translates to:

Func<Task<Obj>> serviceCall = async () => { return await this.client.call(); }

So the return statement is implicit. When you use the brackets you need to specify return explicitly:

Func<Task<Obj>> serviceCall = async () => {
    logger.log("Calling client");
    return await this.client.call();
};