Should You Embrace Strict Typing in PHP 7?

Strict Typing in PHP 7

Introduction

PHP 7 introduced a new feature known as "strict types," characterized by the declare(strict_types = 1) line. This is a game-changer for PHP development, and its effects on coding practices and code quality cannot be understated.

What Strict Types Do

Strict types enable stricter type checking. In default PHP behavior, variables are dynamically typed, meaning they can change types on the fly. However, enabling strict types forces variables to adhere to their declared types.

Any attempt to assign a value of the wrong type will result in a fatal error. This enforces type safety, prevents potential errors and data corruption, and promotes more reliable code.

Impact on Code

When strict types are enabled, the following happens:

• Variables must match their declared types.
• Type casting is not performed automatically.
• Only integers can be implicitly cast to floats.
• Return values must match the declared type.

Consider the following example:

<code class="php">declare(strict_types = 1);

function addNumbers(int $a, float $b) {
  return $a + $b;
}

$result = addNumbers(1.4, '2'); // Strict mode throws an error (cannot convert string to float)</code>

Benefits of Strict Typing

• Code Safety: Strict types prevent type errors, which can lead to runtime exceptions and unexpected results.
• Documentation: Type declarations act as documentation, clearly indicating the expected types for variables and function parameters.
• Error Detection: Earlier error detection helps catch type-related issues during development, reducing the risk of production bugs.
• Code Clarity: Well-defined types enhance code readability and understanding.

Should You Use Strict Typing?

In most cases, enabling strict typing is highly recommended. It promotes code safety, reduces debugging time, and improves overall code quality. It is particularly beneficial for large projects with many contributors or legacy code.

However, there may be specific situations where disabling strict types is necessary, such as when interacting with third-party code that does not adhere to strict typing rules. In such cases, a mix of strict and non-strict typing can be used selectively.

When in doubt, enable strict typing and only disable it when necessary. This practice ensures a more secure and reliable PHP codebase.

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