Why closures matter in PHP - See It in Action

Why closures matter in PHP

📖 Scenario: Imagine you are building a simple PHP program to manage a list of tasks. You want to create a way to filter tasks based on their priority using a special function that remembers the priority level you want to filter by. This is where closures in PHP become very useful.

🎯 Goal: You will create a closure in PHP that remembers a priority level and then use it to filter tasks. This will show why closures matter: they let you keep some data inside a function for later use.

📋 What You'll Learn

Create an array called $tasks with specific tasks and their priorities

Create a variable called $priorityFilter to hold the priority level to filter

Create a closure called $filterTasks that uses use to remember $priorityFilter

Use array_filter with $filterTasks to get tasks matching the priority

Print the filtered tasks

💡 Why This Matters

🌍 Real World

Closures help keep some data inside a function, which is useful when you want to create small, reusable pieces of code that remember settings or filters. This is common in web apps, data processing, and event handling.

💼 Career

Understanding closures is important for PHP developers because many modern PHP frameworks and libraries use closures for callbacks, event listeners, and filtering data efficiently.

1

Create the tasks array

Create an array called $tasks with these exact entries: 'Buy groceries' => 'high', 'Clean house' => 'low', 'Pay bills' => 'medium', 'Call mom' => 'high'.

PHP

# Create the tasks array with exact entries
# Your code here

Need a hint?

Use square brackets [] to create the array with keys and values.

2

Set the priority filter

Create a variable called $priorityFilter and set it to the string 'high'.

PHP

 'high',
    'Clean house' => 'low',
    'Pay bills' => 'medium',
    'Call mom' => 'high'
];

# Create the priority filter variable
# Your code here

Need a hint?

Use = to assign the string 'high' to $priorityFilter.

3

Create the closure to filter tasks

Create a closure called $filterTasks that takes one parameter $priority and uses use ($priorityFilter) to remember the $priorityFilter variable. The closure should return true if $priority equals $priorityFilter, otherwise false.

PHP

 'high',
    'Clean house' => 'low',
    'Pay bills' => 'medium',
    'Call mom' => 'high'
];

$priorityFilter = 'high';

# Create the closure $filterTasks using use ($priorityFilter)
# Your code here

Need a hint?

Use function($priority) use ($priorityFilter) to create the closure that remembers $priorityFilter.

4

Filter and print the tasks

Use array_filter with $tasks and $filterTasks to create a new array called $filteredTasks. Then print $filteredTasks using print_r.

PHP

 'high',
    'Clean house' => 'low',
    'Pay bills' => 'medium',
    'Call mom' => 'high'
];

$priorityFilter = 'high';

$filterTasks = function($priority) use ($priorityFilter) {
    return $priority === $priorityFilter;
};

# Filter tasks and print the result
# Your code here

Need a hint?

Use array_filter($tasks, $filterTasks) to get tasks with priority 'high'. Then use print_r to display the filtered tasks.