# Code Smell 17 - Global Functions

*Discouraged by Object-Oriented Programming, Many mixed languages support it. And developers abuse them.*

> TL;DR: Global functions bring a lot of coupling. Don't use them.

# Problems

*   Coupling
    
*   Readability
    
*   Maintainability
    
*   Testability
    

# Solutions

*   Wrap the function in a context object.
    

# Examples

*   External Resources Access, Database access, Time and Operating System resources.
    

# Sample Code

## Wrong

```php
<?

class Employee {
    function taxesPayedUntilToday() {
        return database()->select(
            "SELECT TAXES FROM EMPLOYEE".
            " WHERE ID = " . $this->id() .
            " AND DATE < " . currentDate());
    }
}
```

## Right

```php
<?

final class EmployeeTaxesCalculator {
    function taxesPayedUntilToday($context) {
        return $context->SelectTaxesForEmployeeUntil(
            $this->ssn,
            $context->currentDate());
    }
}
```

# Detection

Many modern languages avoid them. For the permissive ones, scope rules can be applied and automatically checked.

# Tags

*   Global
    

# Conclusion

Structured programming considers global functions **harmful**. Yet, we can observe some bad practices cross paradigm boundaries.

# Relations

*   Singleton and Classes are global points of access.
    

%[https://maximilianocontieri.com/singleton-the-root-of-all-evil] 

# More Info

*   [Wikipedia](https://en.wikipedia.org/wiki/Global_variable)
    

# Credits

Photo by [Mae Mu](https://unsplash.com/@picoftasty) on [Unsplash](https://unsplash.com/s/photos/spaghetti)

* * *

> The road to programming hell is paved with global variables.

*Steve McConnell*

%[https://maximilianocontieri.com/software-engineering-great-quotes] 

* * *

This article is part of the CodeSmell Series.

%[https://maximilianocontieri.com/how-to-find-the-stinky-parts-of-your-code] 

*Last update: 2021/06/26*