Middle Man

Also Known As

TL;DR

Explanation

The Middle Man smell occurs when a class primarily exists to forward calls to another class, offering no additional logic or value. It arises from over-application of delegation or from classes that were once more substantial but had their behaviour stripped out. The remedy is typically to remove the intermediary and call the delegate directly (inline delegation), or if the class is a legitimate abstraction, to add real behaviour to justify its existence.

Common Misconception

Why It Matters

Common Mistakes

• Service classes that are pure pass-throughs to a repository with no added logic.
• Facade classes that expose every method of the subsystem 1:1 without simplification.
• Not removing middle men during refactoring — they accumulate when classes are extracted but the original is never deleted.
• Over-using delegation patterns from DDD without checking whether each layer adds value.

Code Examples

// UserManager just delegates every call — pointless layer
class UserManager {
    public function __construct(private UserRepository \$repo) {}
    public function find(int \$id): ?User          { return \$this->repo->find(\$id); }
    public function save(User \$u): void           { \$this->repo->save(\$u); }
    public function delete(int \$id): void         { \$this->repo->delete(\$id); }
}

// Remove the middle man — inject UserRepository directly where needed
class UserController {
    public function __construct(private UserRepository \$users) {}
    // use \$this->users directly — no useless delegation layer
}

References

• ↗ https://refactoring.guru/smells/middle-man

Tags

Related Terms