Code Smell 228 - Multiple Classes per File

More than one class is a mess

TL;DR: Follow the separation of concerns principle and file organization

Problems

• Code Organization

• Coupling

• Autoloading problems

• Debugging

• Version control and merge conflicts

Solutions

1. Declare a single class per file

2. Use name scoping

Context

In languages that declare classes using a file system, having one class per file is generally considered a best practice.

This approach helps improve code organization and maintainability and reduces potential issues.

You can organize namespaces into separate directories within your project structure.

This way, you can maintain a logical and efficient codebase while avoiding the issues of declaring multiple classes in a single file.

Sample Code

Wrong

<?

namespace MyNamespace;

class Class1 {
    public function sayHello() {
        echo "Hello from Class1!\n";
    }
}

class Class2 {
    public function sayHello() {
        echo "Hello from Class2!\n";
    }
}

Right

<?

namespace MyNamespace;

class Class1 {
    public function sayHello() {
        echo "Hello from Class1!\n";
    }
}

<?

namespace MyNamespace;

class Class2 {
    public function sayHello() {
        echo "Hello from Class2!\n";
    }
}

Detection

[X] Automatic

Many standards enforce this rule

Tags

• Coupling

Conclusion

Keep your code organized and follow known standards

Relations

Code Smell 48 - Code Without Standards

More Info

Wikipedia Namespaces

Sonar Source

Disclaimer

Code Smells are my opinion.

Credits

Photo by Marjan Blan on Unsplash

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Without requirements or design, programming is the art of adding bugs to an empty text file.

Louis Srygley

Software Engineering Great Quotes

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This article is part of the CodeSmell Series.

How to Find the Stinky Parts of your Code