PHP8.1 introduces improvements to Generators

PHP8.1 introduced improvements to Generators

Generators are a powerful feature introduced in PHP 5.5, which provides a more efficient way to implement iterators. In PHP 8.1 version, Generators have undergone some important improvements, bringing more convenience and flexibility to developers. In this article, we explore these improvements and illustrate their use with code examples.

1. Returning key names and key values

In versions prior to PHP 8.1, Generators could only return key values ​​or key names. This may not be flexible enough in some application scenarios, and other methods need to be used to achieve the need to return key names and key values ​​at the same time. In PHP 8.1, we can use the new yield as syntax to get both the key name and the key value. The following is an example:

function myGenerator()
{
    yield 'a' => 1;
    yield 'b' => 2;
    yield 'c' => 3;
}

$generator = myGenerator();

foreach ($generator as $key => $value) {
    echo "$key => $value" . PHP_EOL;
}

Run the above code, you will get the following output:

a => 1
b => 2
c => 3

Through the yield as syntax, we can obtain the key name and key value at the same time when traversing the iterator, greatly Improved code simplicity and readability.

2. Generator warm-up

In versions prior to PHP 8.1, when we create a Generator object, it will start executing immediately and cannot be paused. In some cases, we want to perform some warm-up operations before actually starting to use the Generator object.

In PHP 8.1, a new method named send() was added for starting a Generator object and pausing its execution. We can perform the necessary initialization work before the generator object is started, and then use the send() method to resume the execution of the generator when needed. Here is an example:

function myGenerator()
{
    $data = yield; // 等待 send() 方法的传值
    yield $data;
}

$generator = myGenerator();

$generator->send(123);

foreach ($generator as $value) {
    echo $value . PHP_EOL;
}

Run the above code, you will get the following output:

123

By using the send() method, passing parameters before the generator object is started, we can generate Perform necessary operations during the execution of the processor to improve the flexibility and scalability of the code.

3. Loose matching of parameter types

Before PHP 8.1, if the key name and key value type of the generator do not exactly match the type of the foreach loop variable, a strict type error will occur. In PHP 8.1, relaxed matching of parameter types was introduced, and errors will no longer be thrown when the type can be cast.

The following is an example:

function myGenerator()
{
    yield 1 => 'a';
    yield 2 => 'b';
    yield 3 => 'c';
}

$generator = myGenerator();

foreach ($generator as $index => $letter) {
    echo $index . ' => ' . $letter . PHP_EOL;
}

Run the above code, you will get the following output:

1 => a
2 => b
3 => c

As you can see, the key name of the generator is an integer, but The type of the foreach loop variable is string. In PHP 8.1, this situation will no longer report an error, but will perform type conversion and output the result normally.

Summary:

The improvements to Generators introduced in PHP 8.1 provide developers with more flexibility and convenience. We can use the yield as syntax to obtain both key names and key values, implement the generator's preheating operation through the send() method, and loosely match parameter types when the types do not match exactly. These improvements make Generators more powerful and easier to use in practical applications.

The above is the improvement and sample code of Generators introduced in PHP 8.1. I hope this article helps you understand and use Generators.

The above is the detailed content of PHP8.1 introduces improvements to Generators. For more information, please follow other related articles on the PHP Chinese website!