Урок 14: "Основы Dart - асинхронность часть вторая (async/await)"

Summary

This tutorial explores the concept of asynchronous programming in Python, focusing on `async`, `await`, and `future` to manage asynchronous operations. It begins with a basic example of summing numbers synchronously and then moves to asynchronous execution using `future` to handle operations in the background. The script demonstrates the advantages of using asynchronous programming to prevent blocking, with practical examples of when to use `async` and `await`. The tutorial also covers potential pitfalls and the importance of managing tasks efficiently to improve code readability and performance.

Takeaways

• 😀 Basic synchronous code is shown with a simple summing function, demonstrating how Python handles basic arithmetic operations.
• 😀 The tutorial introduces the concept of 'Future' objects, which allow asynchronous operations to be handled in Python.
• 😀 The function is refactored to demonstrate how to use 'async' and 'await' to convert synchronous code into asynchronous code.
• 😀 The 'Future' object is used to delay execution and allow other code to run while waiting for results, enhancing performance.
• 😀 The tutorial emphasizes the importance of using the 'await' keyword to pause execution of functions until the result of an asynchronous task is available.
• 😀 The speaker demonstrates how to use the 'asyncio' library to manage asynchronous tasks and how it works with 'Future' objects.
• 😀 An important distinction is made between synchronous and asynchronous programming, highlighting how async functions allow for non-blocking behavior.
• 😀 A practical example is given where the async function calculates values sequentially but allows other tasks to execute concurrently.
• 😀 The speaker discusses potential pitfalls of using asynchronous functions, particularly the temptation to apply 'await' too broadly when it's unnecessary.
• 😀 A refined version of the code is shown using async functions in a more practical context, demonstrating their application in real-world scenarios.

Q & A

What is the main topic discussed in the video?

The video focuses on explaining asynchronous programming concepts, specifically using 'async' and 'await' keywords in Python, along with the demonstration of how to use futures to handle asynchronous operations.

What is the initial function demonstrated in the video?

The initial function demonstrated is a simple summation function, which takes two arguments, adds them together, and returns the result.

Why is the 'future' object introduced in the script?

The 'future' object is introduced to demonstrate asynchronous execution. It allows the function to execute in the background and return a future result, rather than blocking the program until the result is computed.

How is the 'asyncio.Future' used in the example?

In the example, 'asyncio.Future' is used to wrap the result of a summation operation, making it an asynchronous task. The 'future' object holds the result, which will be available once the asynchronous operation completes.

What does the 'async' keyword do in Python?

The 'async' keyword is used to define an asynchronous function in Python. This means the function will return a 'future' object that will execute asynchronously, allowing the program to continue with other tasks while waiting for the function's result.

What role does the 'await' keyword play in asynchronous programming?

The 'await' keyword is used within an asynchronous function to pause the execution until the 'future' object has finished its task. It effectively allows the program to wait for the completion of asynchronous operations before proceeding.

How is the 'asyncio' library utilized in the example?

The 'asyncio' library is used to manage asynchronous tasks. In the video, it is used to handle asynchronous execution, allowing functions to run in parallel without blocking the main thread.

What issue is encountered when trying to use the 'future' without awaiting it?

The issue encountered is that the function attempts to use the result of the 'future' before it has finished executing, leading to an error due to the absence of the result. This can be resolved by using 'await' to ensure the program waits for the result.

How does the 'async' and 'await' structure improve code readability?

The 'async' and 'await' keywords provide a clear and concise way to write asynchronous code, making it easier to understand and maintain compared to using callbacks or complex threading mechanisms.

What are the advantages of using asynchronous programming as shown in the video?

The advantages of asynchronous programming include improved efficiency by allowing the program to perform other tasks while waiting for operations to complete, preventing the program from being blocked or stuck on slow operations, and enhancing the responsiveness of applications.