memoize | Package memoize caches return values of functions | Caching library

Let's take a look at a worst case scenario, i.e. the palindrome check will not allow us to have an early out.

For writing down the recurrence relation, let's say n = end - start, so that n is the length of the sequence to be processed. I'll assume the indexed array accesses are constant time.

is_palindrome will check for palindromity in O(end - start) = O(n) steps.

dfs_helper for a subsequence of length n, calls is_palindrome once and then has 2n recursive calls of lengths 0 through n - 1, each being called two times, plus the usual constant overhead that I will leave out for simplicity.

So, we have

This doesn't work becuase nextjs api routes are "serverless", which means the state that memoize is supposed to remember is destroyed after HTTP call.

The serverless solution is to use a separate service for caching, which is accessible from your api route.

Otherwise, you may need to look at using a custom server.

Images is reloaded because you turn on "Disable cache" option in Devtools - Network. Turn off this option will solve your problem.

Memoization is a concept. You can store it wherever you want, in my example below, I store it in my Fibonacci List, and take it from there.

Using Daniel P. Friedman's memoizing tail

The only real issue (from what I see) is that getSomeData is a poor mock of async functionality, as it doesn't return a promise.

The value passed to useRef is only the initial value, but if it's a function invokation it will actually be called each render. Not so sure about the rest of your question. Each hook exists for a specific purpose. Pick the one that serves your needs.

I have a scenario where I need to store the output of a function throughout the component life cycle.

To me the clear choice is the useMemo hook to memoize the result value of a possibly expensive function call.

It's not regularly updated so useState doesn't fit. If you decided to store it in state and ever needed to updated it, you would need an useEffect hook with dependency and recompute a new value and call the state updater function. This is essentially the useMemo hook.

If you decided to store it in a React ref then you'd again need to pair that with a useEffect with a dependency to update the ref.current value to keep it updated, and this, again, essentially gets you the useMemo hook.

Since you are really looking to optimize a custom hook that provides a static unique id for the life of the component:

1. Using useMemo

You can easily serialize/deserialize vavr objects to/from JSON with jackson. What you need to do is to register VavrModule on the instance of the ObjectMapper:

So I solved it by following these steps:

1. Changed my java --version to 15.0.2
2. Changed my distributionUrl(./android/gradle/wrapper/gradle-wrapper.properties directory) to 6.7 like : https\://services.gradle.org/distributions/gradle-6.7-all.zip
3. in ./android I ran ./gradlew clean
4. in ./android I ran rm -rf ~/.gradle/caches/
5. in project folder I ran react-native run-android again