Скачать или смотреть How to Call a Recursive Lambda Expression in Kotlin

Discover how to effectively call a recursive lambda expression in Kotlin to handle requests and manage indefinite retries with practical examples.
---
This video is based on the question https://stackoverflow.com/q/67801853/ asked by the user 'Hamza Sharaf' ( https://stackoverflow.com/u/11784905/ ) and on the answer https://stackoverflow.com/a/67802012/ provided by the user 'Sweeper' ( https://stackoverflow.com/u/5133585/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Calling a recursive lambda expression

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Calling a Recursive Lambda Expression in Kotlin

When working with asynchronous operations or callbacks in Kotlin, it's common to encounter scenarios where you may need to repeat a request until a certain condition is met. In this guide, we will dive into this problem and explore how to handle recursive lambda expressions in Kotlin. Let's start with a brief overview of the problem at hand.

The Problem

You have a function that sends a request and accepts a lambda expression as a callback. The callback returns a boolean indicating whether the request was successful. The challenge arises when you want to keep making requests until you receive a success response. A naive approach might lead to infinite loops or stacks getting too deep due to unhandled recursion.

Example Function

Here’s a basic outline of our request function:

[[See Video to Reveal this Text or Code Snippet]]

And we use this function in our main method like this:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to continue making these requests indefinitely if the previous one fails. But how do we accomplish this safely and effectively?

The Solution

Calling main Recursively

One straightforward method is to call the main function again when you don't receive a successful result. Here is how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

This will continue making requests but will eventually lead to a stack overflow if you don't have a base case since it will keep re-invoking main endlessly.

Using a Separate Recursive Function

To avoid clutter in the main function and prevent potential stack overflow, it’s better to encapsulate the request logic in a separate function that handles the requests until a success is achieved. This is a cleaner approach:

[[See Video to Reveal this Text or Code Snippet]]

Adding a Maximum Number of Attempts

While the above solution works, it lacks a safety net. If the request always fails, it will keep calling itself indefinitely. To manage this, we can introduce a maxTries parameter to limit the number of attempts:

[[See Video to Reveal this Text or Code Snippet]]

Final Implementation

Here is what the complete implementation looks like:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In conclusion, calling recursive lambda expressions allows us to create effective retry mechanisms for handling asynchronous tasks in Kotlin. By structuring our requests properly and implementing safety checks such as maximum retries, we can ensure our applications remain robust and user-friendly. Experiment with these patterns and find what works best for your specific use case. Happy coding!