承诺的英文，Promise: The English translation

Promise: The English Translation

Promise: The English Translation

Promise is a programming construct that is used to handle success and failure values. It is a way to ensure that a function or method produces the desired result, regardless of whether it succeeds or fails. In many programming languages, including JavaScript, Python, and C++, the concept of a Promise is used to represent the eventual result of a computation or operation.

In English, the word "Promise" is made up of two words: "promise" and "promise." "Promise" comes from the Old French word "promise," which means "to promise or to commit." "Promise" is also derived from the Latin word "promissum," meaning "a promise or a commitment." So, in a sense, a Promise is a promise or a commitment.

The Promise Concept

The Promise concept is based on the idea of a "Promise-based programming paradigm." This means that a programmer writes code that makes a Promise, and then the program can use the "then" keyword to specify what should happen if the Promise is successful or if it is not successful.

For example, consider the following JavaScript code that adds two numbers together and returns a Promise:
function add(a, b) {
return new Promise((resolve, reject) => {
let result = a + b;
if (result === undefined) {
reject(new Error("The result is undefined"));
}
});
});
}
add(2, 3)
.then(result => console.log(result))
.catch(error => console.error(error));

In this example, the "add" function takes two arguments (a and b) and returns a new Promise. The function then uses the "result" variable to store the result of the addition operation, and the "resolve" function to specify that the Promise should resolve with the result (4 in this case). If an error occurs during the addition operation, the Promise will reject with the error.

Promise Using JavaScript

In JavaScript, the Promise concept is used extensively to handle success and failure values. The "Promise" object is a built-in object in JavaScript, and it has methods for creating and manipulating Promises.

The "Promise" object has a number of methods that can be used to create and manipulate Promises. The most commonly used method is "all," which is used to create a Promise that is resolved when all of the Promises in an iterable object are resolved. Here is an example:
const promise1 = add(2, 3);
const promise2 = add(4, 5);
const allPromise = promise1.all([promise2]);
allPromise.then(results => console.log(results));

In this example, the "add" function is used to create two separate Promises (promise1 and promise2). The "all" method is then used to create a new Promise that is resolved when all of the Promises in the iterable object (promise1 and promise2) are resolved. Finally, the "then" method is used to specify what should happen if the Promise is resolved with the results of the Promise (the values of the addition operation).

Another commonly used method is "reject," which is used to create a Promise that is rejected with a specified error. Here is an example:
const promise = new Promise((resolve, reject) => {
setTimeout(() => {
const result = Math.random() console.log(result));

In this example, the "Math.random" function is used to generate a random number between 0 and 1. If the number is less than 0.5, the Promise is resolved with the string "Hello, World!" (which is the default result for a Promise that resolves successfully). If the number is greater than or equal to 0.5, the Promise is rejected with the error.

Promise Using Python

In Python, the Promise concept is used extensively to handle success and failure values. The "asyncio" module, which is part of the standard library in Python, provides Promises that can be used to handle tasks and exceptions.

The "asyncio" module has a number of functions and classes that can be used to create and manipulate Promises. The most commonly used functions are "Promise" and "async with.", which are used to create and resolve Promises, respectively.

The "Promise" function is similar to the one described in the previous example, but with some differences. For example, the "Promise" function in Python is not a built-in object, and it is defined in the "asyncio" module rather than the standard library.

Here is an example of how to use the "Promise" function in Python to create and resolve a Promise:
import asyncio
async def add(a, b):
return await asyncio.sleep(2)
async def do_something():
return await add(2, 3)
async def runasyncfunction():
result = await do_something()
console.log(result)
asyncio.run(runasyncfunction())
Promise Using C++

In C++, the Promise concept is used extensively to handle success and failure values. The C++11 standard introduced the "std::promise" library, which provides a set of classes and functions for creating and manipulating Promises.

The "std::promise" library has a number of classes and functions that are similar to those in the "Promise" example described in the previous section. Here is an example of how to use the "std::promise" library to create and resolve a Promise:
#include
#include
#include
template
class Promise {
public:
Promise() : success(false) {}
T result;
bool is_fulfilled()
void fulfill(T result) {
success = true;
this->result = result;
}
void reject(const std::error_code& error) {
success = false;
throw error;
}
private:
std::unique_ptr executor;
std::memory::optimized result;
bool success;
};
int main() {
std::promise p(std::move(add(2, 3)));
p.fulfill(42);
std::cout