ExcessiveParameterList

Emitted when a method has too many parameters, indicating the method is doing too much or needs a parameter object.

<?php
public function createUser(
    string $firstName,
    string $lastName,
    string $email,
    string $password,
    string $phone,
    string $address,
    string $city,
    string $country,
    string $postalCode,
    bool $newsletter
): User {
    // ...
}

Why this is bad

Hard to call: Easy to mix up parameter order
Hard to read: Method signature is overwhelming
Hard to extend: Adding parameters makes it worse
Sign of SRP violation: Method likely does too much

How to fix

Use a parameter object or DTO:

<?php
class CreateUserRequest
{
    public function __construct(
        public readonly string $firstName,
        public readonly string $lastName,
        public readonly string $email,
        public readonly string $password,
        public readonly Address $address,
        public readonly bool $newsletter = false,
    ) {}
}

public function createUser(CreateUserRequest $request): User
{
    // Clean and focused
}

Threshold

Level	Parameters
🍝 Piccolo	≤5
🍝🍝 Medio	6-10
🍝🍝🍝 Grande	11-15
🍝🍝🍝🍝 Mamma Mia!	16+