Yield from

Introduction

The yield from keyword is used in PHP to delegate the generation of values to another generator. This allows you to chain multiple generators together, creating a pipeline of sorts that can be used to transform or filter data on-the-fly.

Example

Here's an example that demonstrates the use of yield from in PHP:

<?php

function myGenerator()
{
  yield "Hello";
  yield "World";
}

function myOtherGenerator()
{
  yield "!";
}

function myCombinedGenerator()
{
  yield from myGenerator();
  yield from myOtherGenerator();
}

foreach (myCombinedGenerator() as $value) {
  echo $value . " ";
}

In the example above, we have three generator functions: myGenerator(), myOtherGenerator(), and myCombinedGenerator(). The first two generators each produce a single value, while the third generator delegates to the first two generators using the yield from keyword.

When myCombinedGenerator() is called, it first yields the values generated by myGenerator(), and then it yields the values generated by myOtherGenerator(). This creates a sequence of three values: "Hello", "World", and "!".

The foreach loop then uses myCombinedGenerator() to iterate over the sequence of values, producing the output: "Hello World !".

The yield from keyword can be particularly useful when working with nested data structures or when you need to perform a series of transformations on a dataset. By chaining multiple generators together, you can break down complex problems into simpler, more manageable pieces, making your code easier to read and maintain.