Promise2 | c14 compliant cross-platform implementations of promise
kandi X-RAY | Promise2 Summary
kandi X-RAY | Promise2 Summary
c++14 compliant cross-platform implementations of promise.
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Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of Promise2
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Promise2 Examples and Code Snippets
Lines of Code : 38License : Permissive (MIT)
Copyclass EventPollIterator {
private:
ConsumerChan chan;
public:
EventPollIterator() = default;
template
EventPollIterator(String&& opts)
:chan { ConsumerChan::New(std::forward(opts)) }
{}
bool operator != (const EventPollIter // libdispatch
using CurrentThreadContext = ThreadContextImpl::GCD::CurrentThreadContext;
using STLThreadContext = ThreadContextImpl::STL::DetachedThreadContext;
auto promise = Promise::New([]{
// do something in new thread
}, STLThreadContext::Ne include(ExternalProject)
find_package(Git REQUIRED)
# checkout the source code from github
ExternalProject_Add(
Promise2
PREFIX "deps/root/path"
GIT_REPOSITORY https://github.com/0of/Promise2.git
TIMEOUT 10
UPDATE_COMMAND ${GIT_E Community Discussions
Trending Discussions on Promise2
QUESTION
It is asserted the ECMAScript promises is a Promises/A+ implementation, so they have no contradictions. However, I encountered a behaviour of ecma promises which allegedly is out of line with the Promises/A+.
When we call promise1.then(onFulfilled, onRejected) to listen to the promise1's output, we get as a return value another promise (promise2). When the needed callback (onFulfilled/onRejected) was executed and it, in turn, returned some value x, the spec prescribes to resolve it with the defined [[Resolve(promise2, x)]] function. Let's suppose x happened to be a promise itself (x === promise3), then the steps must be taken is the following:
- If
xis a promise, adopt its state:- If
xis pending,promise2must remain pending untilxis fulfilled or rejected.- If/when
xis fulfilled, fulfillpromise2with the same value.- If/when
xis rejected, rejectpromise2with the same reason.
I wonder what if x is finally fulfilled with yet another promise (promise4) (there are not anything in the way of it, are there?). It can be concluded from the spec excerpt that promise2 must be fulfilled with promise4 too. But it is seemingly not so in the ECMAScript world:
ANSWER
Answered 2021-May-26 at 20:29Let's suppose
xhappened to be a promise itself, then the steps must be taken is the following: […]
No, they don't need to be taken - they only may be taken if x is a "promise". These steps are an optional ("allowed", not "required") optimisation:
Note 4:
Generally, it will only be known thatxis a true promise if it comes from the current implementation. This clause allows the use of implementation-specific means to adopt the state of known-conformant promises.
ECMAScript does not treat its own Promises as "known to be conformant", ignoring these steps. They simply treat native promises like all other thenables. Given there is no way to create an ECMAScript Promise that is fulfilled with another promise, this is equivalent to directly adopting the state.
QUESTION
I want to run multiple Promise.all functions in sequence where the second Promise.all starts only after the first Promise.all is returned. I tried to do it using async/await but I noticed that although the result of second Promise.all is displayed after the first one, it is actually running IN PARALLEL (which is not what I want).
In the example,
...ANSWER
Answered 2021-May-25 at 03:00Your 2-second timeout starts executing the moment you create its promise (*). Promise.all doesn't "start" the promises, it merely ensures they are all resolved (or one of them failed) before it will resolve.
In order to make the sequence you desire, you have to create promise6 after values1 has been received.
QUESTION
When making multiple requests concurrently with Promise.allSettled, does the order of the array in the response correspond to the intitial array in the request? Does it maintain the same order regardless of the order in which they settle?
ANSWER
Answered 2021-Apr-26 at 21:52Yes, it is guaranteed. The steps are described in the specification.
On each iteration over the passed iterable, it does
Set resolveElement.[[Index]] to index. Set rejectElement.[[Index]] to index.
where index is the current index in the iterable being iterated over, which then gets passed to the resolver or rejector algorithm. Both the resolver and the rejector does, at the end:
Set values[index] to obj.
where values is the array of resolve values that the whole Promise.allSettled will resolve with.
The nth item in the passed iterable/array will always correspond to the nth item in the resolved array.
QUESTION
I didn't return something in then() callback, In my opinion the output should be 1 5 7 2 6 3 4,but the result is 1 2 5 3 6 7 4, who can tell me why
...ANSWER
Answered 2021-Mar-16 at 19:56Alright, this will be very verbose. Contrary to others, i'll claim, that the execution order for the console.log calls is completely deterministic here. This doesn't always have to be the case with async code, but when there isn't any "real" async code happening, it still often is.
Code numbered for clarity:
QUESTION
I have this code that returns the speed score of a website through google API. As sometimes the value is not correct, i read on a post, that is a good practice to make the request few times and then make the median of the score . How i can make multiple Api request simultaneously ?
I tried something like this
...ANSWER
Answered 2021-Mar-06 at 21:24Your issue here is that medianSpeed isn't returning a promise, so there's nothing to wait for.
If you did return Promise.allSettled... and then did a then block after calling the function: medianSpeed().then(values => {}) then you would get the values back.
I assume that the url variable is coming from somewhere else?
QUESTION
I wanted to make the async function like after 1 second then promise1 is executed and THEN after 0.5 seconds is passed over promise1 executed then promise2 is executed. I tried this but it doesn't work. But the function works after putting resolve(). I got how this work but I am not still sure why it works.
ANSWER
Answered 2021-Jan-16 at 08:12You create a new promise and you never resolve it. You need to put a call to res() inside the setTimeout(). A new promise you manually create is never resolved until you call the resolving function from somewhere inside the promise constructor function. That's just how the promise constructor function works.
QUESTION
I am pretty new in JavaScript technoogies and RxJS and I have the following doubt about how exactly works this code. It is taken from a project on which I am working and it works fine but I need to understand how exactly Promise.all() works and how it is used in this code.
So basically I have this method used to save multiple files on Firebase Store:
...ANSWER
Answered 2021-Jan-05 at 10:48Promise.all
It will take an array of promises and execute them in parallel. It follows the mechanism of all or none
Promise.all([ ...]).then(console.log) will execute if all promises are fulfilled, otherwise it will execute catch Promise.all([ ...]).catch(console.log)
There is one more method Promise.allSettled This will consider a success even one of the promises is failed. return data contains all results with statues
Syntax:-
QUESTION
const promise1 = Promise.resolve(3);
const promise2 = 42;
const promise3 = new Promise((resolve, reject) => {
setTimeout(resolve, 100, 'foo');
});
Promise.all([promise1, promise2, promise3]).then((values) => {
console.log(values);
});
Promise(promise2).then((values) => {
console.log(values);
});
ANSWER
Answered 2020-Dec-18 at 06:37You need to use it like this:
QUESTION
If I have promise running synchronously, how do I want for both of them to finish? Doesn't await only work for a single Promise?
ANSWER
Answered 2020-Dec-06 at 06:01You can use Promise.all to wait for both of them at once
QUESTION
Endpoint is returning 502 in every condition. I think my reponses are correctly structured but I still got 502 Bad Gateway error from my endpoint.
Responses was working when I was not dealing with Promise.all().
Timeout for this function is 30 seconds btw, but it doesn't take that long.
I have a handler like this:
...ANSWER
Answered 2020-Dec-05 at 10:23You should stick to using await or .then, instead of trying to use both.
Since your handler is already async you might as well use await.
I've modified your code below so that it no longer uses .then (not tested).
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