Static Typed vs Non-Static Typed PHP

PHP has long been known as a dynamically typed language. Developers could write flexible, quick-to-deploy code without worrying too much about data types. However, as applications scaled and the need for robustness grew, PHP evolved. With the introduction of scalar type declarations and return types in PHP 7, and more recently with union types and typed properties in PHP 8, the language began supporting static typing features.

What Is Static Typing?

Static typing means that variable types are declared explicitly and checked at compile time (or, in PHP’s case, before execution). Here’s a simple example:

function add(int $a, int $b): int {
   return $a + $b;
}

In this example:

• Both parameters $a and $b must be integers.
• The return type is also strictly an integer.
• If you try to pass a string or a float, PHP will throw a TypeError.

What Is Dynamic Typing?

Dynamic typing means that variable types are determined at runtime. This was PHP’s default behavior for many years.

function add($a, $b) {
   return $a + $b;
}

This function will accept integers, floats, and even numeric strings like "2". PHP will try to coerce the types and execute the operation.

Benefits of Static Typing

1. Better Code Readability
   Explicit type declarations serve as documentation. Developers know exactly what type of data to expect.

2. Improved Tooling and IDE Support
   With static types, IDEs can offer better autocomplete, refactoring tools, and error detection.

3. Fewer Runtime Errors
   Many bugs can be caught early, avoiding unexpected behavior in production.

4. Easier Refactoring
   Knowing variable types helps in safely refactoring large codebases.

Drawbacks of Static Typing

1. More Verbose Code
   You must explicitly declare types, which can add overhead for simple scripts.

2. Less Flexibility
   You lose some of the dynamic nature PHP was originally loved for. Type juggling becomes a liability.

3. Backward Compatibility
   Older PHP libraries and codebases may not use or support static typing.

When to Use Static Typing

• You’re working on a large codebase where bugs are harder to track.
• You’re building a team project where clarity and consistency are vital.
• You’re writing a public library or API where contracts should be enforced.

When to Stick With Dynamic Typing

• You’re prototyping or building a quick MVP.
• You’re maintaining a legacy application.
• You’re writing small scripts or automation tasks where overhead isn’t worth it.

Example: Static vs Dynamic Typing in Practice

// Static typed version
function greet(string $name): string {
   return "Hello, $name!";
}

// Dynamic typed version
function greet($name) {
   return "Hello, $name!";
}

The statically typed version provides immediate feedback if an incorrect type is passed. The dynamic version might fail later or worse, behave unexpectedly.

PHP has come a long way from its purely dynamic roots. With optional static typing, developers now have more tools to write safer, more maintainable code. But with great power comes great responsibility and the choice between static and dynamic typing depends on your project’s needs.