Classes are handy. We can call them and invoke them at any time. Is this good?

TL;DR: Don't use your classes as a global point of access.

Problems

• Coupling

• Classes are global unless we use Namespaces.

• Name polluting

• Static Methods

• Static Constants

• Singletons

Solutions

1. Use namespaces, module qualifiers or similar

2. Avoid namespace polluting, keep the Global names as short as possible.

3. Class single Responsibility is to create instances.

Sample Code

Wrong

<?

final class StringUtilHelper {
    static function reformatYYYYDDMMtoYYYYMMDD($date) {
    }
}

class Singleton {

}

final class DatabaseAccessor extends Singleton {

}

Right

<?

namespace Date;

final class DateFormatter {

    function reformatYYYYDDMMtoYYYYMMDD(Date $date) {
    }
    //function is not static since class single responsibility is to create instances and not be a library of utils

}

namespace OracleDatabase;

class DatabaseAccessor {
    //Database is not a singleton and it is namespace scoped
}

Detection

We can use almost any linter or create dependency rules searching for bad class references.

Tags

• Globals

Conclusion

We should restrict our classes to small domains and expose just facades to the outside. This greatly reduces coupling.

Relations

More info

Credits

Photo by Alfons Morales on Unsplash

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Write shy code — modules that don't reveal anything unnecessary to other modules and that don't rely on other modules' implementations.

Dave Thomas

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This article is part of the CodeSmell Series.