Refactoring Techniques in PHP

Introduction

Hello, Explorer! Today is about refactoring . Consider it as organizing your favorite toys in the toybox. We're going to learn about the Extract Method, Rename Method, and Substitute Algorithm refactorings. Refactoring helps us make our code cleaner and neater while keeping the functionality the same!

Refactoring Overview

Imagine having a complex map. Refactoring transforms it into simpler directions. Our code gets rearranged to make it more readable and efficient without altering what it does. Let's consider a small code snippet before and after refactoring: // Before refactoring function calculate($total, $quantity) {$price = $total / $quantity; $tax = $price * 0.2; $totalPrice = $price + $tax; return $totalPrice;} // After refactoring function calculateTotalPrice($total, $quantity) {$price = calculatePrice($total, $quantity); $tax = calculateTax($price); return $price + $tax;} function calculatePrice($total, $quantity) {return $total / $quantity;} function calculateTax($price) {return $price * 0.2;} Both versions of the code do the same thing, but the latter is simpler and easier to understand!

Understanding the Extract Method

Imagine a large recipe for a complete breakfast. The Extract Method technique is like having separate recipes for eggs, toast, coffee, etc., instead of one large recipe. Take a look at this code: // Before refactoring function greetUser($username) {$username = strtolower(trim($username)); // Prepare the username $message = "Hello, " . $username . "!"; // Prepare the message return $message; // Return the prepared message} // After refactoring function cleanUsername($username) {return strtolower(trim($username)); // Returns a cleaned version of the username} function greetUser($username) {$username = cleanUsername($username); // Clean the username $message = "Hello, " . $username . "!"; // Prepare and return the message return $message;} Here, we moved the username preparation from greetUser into its own function, cleanUsername . Nice and tidy!

Using Rename Method

Clear method names make it easy to understand our code, just as clear street names make navigating a city more accessible. Let's have a look at renaming a method: // Before refactoring function fx($x) {return 3.14 * ($x * $x); // Calculates a value that is pi times the square of x} // After refactoring function calculateCircleArea($radius) {return 3.14 * ($radius * $radius); // Calculates the area of a circle with a given radius} Renaming the function fx to calculateCircleArea makes it easier to understand its purpose.

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PHP

// Before refactoring
function calculate($total, $quantity) {
    $price = $total / $quantity;
    $tax = $price * 0.2;
    $totalPrice = $price + $tax;
    return $totalPrice;
}

// After refactoring
function calculateTotalPrice($total, $quantity) {
    $price = calculatePrice($total, $quantity);
    $tax = calculateTax($price);
    return $price + $tax;
}

function calculatePrice($total, $quantity) {
    return $total / $quantity;
}

function calculateTax($price) {
    return $price * 0.2;
}

// Before refactoring
function calculate($total, $quantity) {
    $price = $total / $quantity;
    $tax = $price * 0.2;
    $totalPrice = $price + $tax;
    return $totalPrice;
}

// After refactoring
function calculateTotalPrice($total, $quantity) {
    $price = calculatePrice($total, $quantity);
    $tax = calculateTax($price);
    return $price + $tax;
}

function calculatePrice($total, $quantity) {
    return $total / $quantity;
}

function calculateTax($price) {
    return $price * 0.2;
}

PHP

// Before refactoring
function greetUser($username) {
    $username = strtolower(trim($username)); // Prepare the username
    $message = "Hello, " . $username . "!"; // Prepare the message
    return $message; // Return the prepared message
}

// After refactoring
function cleanUsername($username) {
    return strtolower(trim($username)); // Returns a cleaned version of the username
}

function greetUser($username) {
    $username = cleanUsername($username); // Clean the username
    $message = "Hello, " . $username . "!"; // Prepare and return the message
    return $message;
}

// Before refactoring
function greetUser($username) {
    $username = strtolower(trim($username)); // Prepare the username
    $message = "Hello, " . $username . "!"; // Prepare the message
    return $message; // Return the prepared message
}

// After refactoring
function cleanUsername($username) {
    return strtolower(trim($username)); // Returns a cleaned version of the username
}

function greetUser($username) {
    $username = cleanUsername($username); // Clean the username
    $message = "Hello, " . $username . "!"; // Prepare and return the message
    return $message;
}

PHP

// Before refactoring
function fx($x) {
    return 3.14 * ($x * $x); // Calculates a value that is pi times the square of x
}

// After refactoring
function calculateCircleArea($radius) {
    return 3.14 * ($radius * $radius); // Calculates the area of a circle with a given radius
}

// Before refactoring
function fx($x) {
    return 3.14 * ($x * $x); // Calculates a value that is pi times the square of x
}

// After refactoring
function calculateCircleArea($radius) {
    return 3.14 * ($radius * $radius); // Calculates the area of a circle with a given radius
}

PHP

// Before refactoring
function findSmallest($numbers) {
    $smallest = PHP_INT_MAX;
    foreach ($numbers as $num) {
        if ($num < $smallest) {
            $smallest = $num;
        }
    }
    return $smallest;
}

// After refactoring
function findSmallest($numbers) {
    return min($numbers); // Returns the smallest number from 'numbers'
}

// Before refactoring
function findSmallest($numbers) {
    $smallest = PHP_INT_MAX;
    foreach ($numbers as $num) {
        if ($num < $smallest) {
            $smallest = $num;
        }
    }
    return $smallest;
}

// After refactoring
function findSmallest($numbers) {
    return min($numbers); // Returns the smallest number from 'numbers'
}

PHP

// Before refactoring
function calculate($total, $quantity) {
    $price = $total / $quantity;
    $tax = $price * 0.2;
    $totalPrice = $price + $tax;
    return $totalPrice;
}

// After refactoring
function calculateTotalPrice($total, $quantity) {
    $price = calculatePrice($total, $quantity);
    $tax = calculateTax($price);
    return $price + $tax;
}

function calculatePrice($total, $quantity) {
    return $total / $quantity;
}

function calculateTax($price) {
    return $price * 0.2;
}

PHP

// Before refactoring
function greetUser($username) {
    $username = strtolower(trim($username)); // Prepare the username
    $message = "Hello, " . $username . "!"; // Prepare the message
    return $message; // Return the prepared message
}

// After refactoring
function cleanUsername($username) {
    return strtolower(trim($username)); // Returns a cleaned version of the username
}

function greetUser($username) {
    $username = cleanUsername($username); // Clean the username
    $message = "Hello, " . $username . "!"; // Prepare and return the message
    return $message;
}

PHP

// Before refactoring
function fx($x) {
    return 3.14 * ($x * $x); // Calculates a value that is pi times the square of x
}

// After refactoring
function calculateCircleArea($radius) {
    return 3.14 * ($radius * $radius); // Calculates the area of a circle with a given radius
}

PHP

// Before refactoring
function findSmallest($numbers) {
    $smallest = PHP_INT_MAX;
    foreach ($numbers as $num) {
        if ($num < $smallest) {
            $smallest = $num;
        }
    }
    return $smallest;
}

// After refactoring
function findSmallest($numbers) {
    return min($numbers); // Returns the smallest number from 'numbers'
}

Introduction

Refactoring Overview

Understanding the Extract Method

Using Rename Method

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Discovering Substitute Algorithm

Lesson Summary