Yield from delegation in PHP - Mini Project: Build & Apply

Yield from delegation

📖 Scenario: Imagine you are organizing a music playlist. You have different smaller playlists for genres like rock and jazz. You want to create one big playlist that plays all songs from these smaller playlists in order.

🎯 Goal: Build a PHP generator that uses yield from to combine multiple smaller playlists into one big playlist.

📋 What You'll Learn

Create two generators for small playlists with exact song names

Create a main generator that uses yield from to delegate to the smaller playlists

Iterate over the main generator to print all songs in order

💡 Why This Matters

🌍 Real World

Combining multiple data sources or streams into one sequence is common in music apps, data processing, and event handling.

💼 Career

Understanding generators and delegation helps write efficient code for handling large data or asynchronous tasks in PHP development.

1

Create the first playlist generator

Write a generator function called rockPlaylist that yields these exact songs in order: 'Bohemian Rhapsody', 'Stairway to Heaven', 'Hotel California'.

PHP

# Your code here

Need a hint?

Use yield inside the function to return each song one by one.

2

Create the second playlist generator

Write a generator function called jazzPlaylist that yields these exact songs in order: 'So What', 'Take Five', 'Blue in Green'.

PHP

<?php
function rockPlaylist() {
    yield 'Bohemian Rhapsody';
    yield 'Stairway to Heaven';
    yield 'Hotel California';
}

# Your code here

Need a hint?

Similar to the first playlist, use yield for each jazz song.

3

Create the main playlist generator using yield from

Write a generator function called mainPlaylist that uses yield from to delegate to rockPlaylist() first, then to jazzPlaylist().

PHP

<?php
function rockPlaylist() {
    yield 'Bohemian Rhapsody';
    yield 'Stairway to Heaven';
    yield 'Hotel California';
}

function jazzPlaylist() {
    yield 'So What';
    yield 'Take Five';
    yield 'Blue in Green';
}

# Your code here

Need a hint?

Use yield from to include all songs from each smaller playlist.

4

Print all songs from the main playlist

Use a foreach loop to iterate over mainPlaylist() and print each song on its own line using echo.

PHP

<?php
function rockPlaylist() {
    yield 'Bohemian Rhapsody';
    yield 'Stairway to Heaven';
    yield 'Hotel California';
}

function jazzPlaylist() {
    yield 'So What';
    yield 'Take Five';
    yield 'Blue in Green';
}

function mainPlaylist() {
    yield from rockPlaylist();
    yield from jazzPlaylist();
}

# Your code here

Need a hint?

Use foreach (mainPlaylist() as $song) and echo $song . "\n"; to print each song.