Code Smell 66 - Shotgun Surgery

Say it only once

28 April, 2023

Contributors

Maxi Contieri

@mcsee

TL;DR: Don't fire!

Say it only once

Problems

Bad Responsibilities Assignments
Code Duplication
Maintainability
Single Responsibility Violation.
Copy-pasted code.

Solutions

Refactor

Sample Code

Wrong

<?

final class SocialNetwork {

    function postStatus(string $newStatus) {
        if (!$user->isLogged()) {
            throw new Exception('User is not logged');
        }
        // ...
    }

    function uploadProfilePicture(Picture $newPicture) {
        if (!$user->isLogged()) {
            throw new Exception('User is not logged');
        }
        // ...
    }

    function sendMessage(User $recipient, Message $messageSend) {
        if (!$user->isLogged()) {
            throw new Exception('User is not logged');
        }
        // ...
    }
}

Right

<?

final class SocialNetwork {

    function postStatus(string $newStatus) {
        $this->assertUserIsLogged();
        // ...
    }

    function uploadProfilePicture(Picture $newPicture) {
        $this->assertUserIsLogged();
        // ...
    }

    function sendMessage(User $recipient, Message $messageSend) {
        $this->assertUserIsLogged();
        // ...
    }

    function assertUserIsLogged() {
        if (!$this->user->isLogged()) {
            throw new Exception('User is not logged');
            // This is just a simplification to show the code smell
            // Operations should be defined as objects with preconditions etc.
        }
    }
}

Detection

Some modern linters can detect repeated patterns (not just repeated code) and also while performing our code reviews we can easily detect this problem and ask for a refactor.

Conclusion

Adding a new feature should be straightforward in our model maps 1:1 to real-world and our responsibilities are in the correct places. We should be alert for small changes spanning several classes.

More Info

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

(Refactoring Guru)[https://refactoring.guru/es/smells/shotgun-surgery]

(NDpend Blog)[https://blog.ndepend.com/shotgun-surgery]

(Dzone)[https://dzone.com/articles/code-smell-shot-surgery]

Credits

Photo by William Isted on Unsplash

Duplication is the primary enemy of a well-designed system.

Robert Martin

Software Engineering Great Quotes

This article is part of the CodeSmell Series.

How to Find the Stinky Parts of your Code