You're describing a variant of the interpreter pattern. I've used similar in task scheduling contexts, and the key drawback is you no longer have useful stack traces.
I haven't done any formal research on the approach, though. I will caution you that async functions are already widely used enough (particularly in Node) they're unlikely to go anywhere beyond something drastic. On Sat, Dec 16, 2017, 00:07 Pranay Prakash <[email protected]> wrote: > Hey all, > > I was just reading the docs for `redux-saga` where I encountered a nice > design pattern for a saga which is (correct me if I'm wrong) a > regular javascript generator function that yields the intent to call a > function (instead of actually calling a function) until it goes through all > the steps. If that doesn't make sense, consider this simple function: > > ``` > async function findFriends() { > const myId = getMyID(); > const myUser = await fetchUser(myId); > return myUser.friends; > } > ``` > > instead of actually making the function calls needed, we can instead have > a function that does something like this: > > > ``` > function* findFriends() { > const myId = yield { fn: getMyID }; > const myUser = yield { fn: fetchUser, args: [myId] }; > return myUser.friends; > } > ``` > > This is a pure generator function that doesn't actually do anything, but > has all the necessary information to recreate the original function[1] (or > have a library "trampoline" through the function and make all the necessary > calls for you) > > A HUGE plus of the second version of the function is that it's *easily* > testable (unlike the first one). Pure functions are easier to test. Testing > this is simply a matter of calling `.next()`, getting the "intent", making > sure the right intent was yielded (good enough for unit testing) and > calling `.next()` again with the "mock" value, you want to return and > continue to test. > > An observation to make here is that you can transform the original version > of this code (easy, normal code to write) to the latter (easy code to > test). So, what about having some sort of babel transform perhaps that can > convert the first to the second but only in the context of unit tests. You > write code the normal way as you would for your application and don't worry > about test suite implementation details (mocking/dependency > injection/etc.), and when you want to test, simply import your function > (which gets converted to a generator) and step through it to test different > scenarios. > > I personally think this is a super clean way to do testing since the tests > never interfere with how you actually write the code AND you don't have to > explicitly mock. > > Does anyone have thoughts on this / prior research (or knows about an > existing implementation of this)? > > Cheers, > Pranay > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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