Rewrite error catching higher order function to catch async errors?

问题

Here I have a function that works well for catching sync errors, and doing something with them before re-throwing them.

    function logExceptions<T extends (...args: any[]) => any>(func: T): (...funcArgs: Parameters<T>) => ReturnType<T> {
      return (...args: Parameters<T>): ReturnType<T> => {
        try {
          return func(...args);
        } catch (err) {
          console.log(func.name + " caused an error")
          throw err;
        }
      };
    }

function syncExample() { 
  throw new Error()
}

logExceptions(syncExample)();

console.log

"syncExample caused an error"

Can I rewrite this function to become async agnostic and also work for async functions?

async function asyncExample() { 
  throw new Error()
}
logExceptions(asyncExample)();

desired console.log

"asyncExample caused an error"

actual console.log

""

回答1:

Can I rewrite this function to become async agnostic and also work for async functions?

No. While you could try to overload it and detect whether the function would return a promise or not, that's very fragile. Better write a separate function for wrapping asynchronous functions:

function logExceptions<T extends any[], U>(func: (...args: T) => PromiseLike<U>): (...args: T) => Promise<U> {
  return async (...args) => {
    try {
      return await func(...args);
    } catch (err) {
      console.log(func.name + " caused an error")
      throw err;
    }
  };
}

回答2:

Agree with @Bergi about the new function.

---

Typescript doesn't like it when we return directly the ReturnType in case of async method use. I guess it's because I havent specified that ReturnType must be of type Promise, but I've found now way how to specify it.

type ReturnType any> = T extends (...args: any) => infer R ? R : any Obtain the return type of a function type

The return type of an async function or method must be the global Promise type.(1064)

I've found a turnaround by extracting what's templated inside of the Promise and redeclaring it.

type ExtractPromiseTemplate<T> = T extends PromiseLike<infer U> ? U : T

function logExceptions<T extends (...args: any[]) => ReturnType<T>>(func: T): (...funcArgs: Parameters<T>) => Promise<ExtractPromiseTemplate<ReturnType<T>>> {
      return async (...args: Parameters<T>): Promise<ExtractPromiseTemplate<ReturnType<T>>> => {
        try {
          console.log('Will call now');
          const ret = await func(...args);

          return ret as ExtractPromiseTemplate<ReturnType<T>>;
        } catch (err) {
          console.log(func.name + " caused an error");

          throw err;
        }
      };
    }

async function asyncExample() { 
  throw new Error('Example')
}

logExceptions(asyncExample)();

---

Call the following code to test the validity of the returned value :

type ExtractPromiseTemplate<T> = T extends PromiseLike<infer U> ? U : T

function logExceptions<T extends (...args: any[]) => ReturnType<T>>(func: T): (...funcArgs: Parameters<T>) => Promise<ExtractPromiseTemplate<ReturnType<T>>> {
      return async (...args: Parameters<T>): Promise<ExtractPromiseTemplate<ReturnType<T>>> => {
        try {
          console.log('Will call now');
          const ret = await func(...args);

          return ret as Promise<ExtractPromiseTemplate<ReturnType<T>>>;
        } catch (err) {
          console.log(func.name + " caused an error");

          throw err;
        }
      };
    }

async function asyncExample():Promise<string> { 
  return 'a';
}

(async() => {
  const ret = await logExceptions(asyncExample)();
})();

---

---

New playground for @bergi comment

来源：https://stackoverflow.com/questions/62325850/rewrite-error-catching-higher-order-function-to-catch-async-errors