tolry/phpcs-calisthenics-rules

Object Calisthenics rules for PHP_CodeSniffer

Object Calisthenics rules for PHP_CodeSniffer

Object Calisthenics are set of rules in object-oriented code, that focuses of maintainability, readability, testability and comprehensibility. We're pragmatic first - they are easy to use all together or one by one.

Why Should You Use This in Your Project?

Read post by William Durand or check presentation by Guilherme Blanco.

Install

composer require object-calisthenics/phpcs-calisthenics-rules

Usage

Via CLI

vendor/bin/phpcs src tests -sp \
--standard=vendor/object-calisthenics/phpcs-calisthenics-rules/src/ObjectCalisthenics/ruleset.xml

The Best to Start With: Single Sniff via CLI

vendor/bin/phpcs src tests -sp \
--standard=vendor/object-calisthenics/phpcs-calisthenics-rules/src/ObjectCalisthenics/ruleset.xml \
--sniffs=ObjectCalisthenics.Classes.ForbiddenPublicProperty

---

Implemented Rule Sniffs

1. Only X Level of Indentation per Method

❌

foreach ($sniffGroups as $sniffGroup) {
    foreach ($sniffGroup as $sniffKey => $sniffClass) {
        if (! $sniffClass instanceof Sniff) {
            throw new InvalidClassTypeException;
        }
    }
}

👍

foreach ($sniffGroups as $sniffGroup) {
    $this->ensureIsAllInstanceOf($sniffGefroup, Sniff::class);
}

// ...
private function ensureIsAllInstanceOf(array $objects, string $type)
{
    // ...
}

Apply in CLI?

--sniffs=ObjectCalisthenics.Metrics.MaxNestingLevel

🔧 Configurable

• in CodeSniffer XML
• in EasyCodingStandard NEON

---

2. Do Not Use "else" Keyword

❌

if ($status === self::DONE) {
    $this->finish();
} else {
    $this->advance();
}

👍

if ($status === self::DONE) {
    $this->finish();
    return;
}

$this->advance();

Apply in CLI?

--sniffs=ObjectCalisthenics.ControlStructures.NoElseSniff

---

5. Use Only One Object Operator (->) per Line

❌

$this->container->getBuilder()->addDefinition(SniffRunner::class);

👍

$containerBuilder = $this->getContainerBuilder();
$containerBuilder->addDefinition(SniffRunner::class);

Apply in CLI?

--sniffs=ObjectCalisthenics.CodeAnalysis.OneObjectOperatorPerLine

🔧 Configurable

• in CodeSniffer XML
• in EasyCodingStandard NEON

---

6. Do not Abbreviate

This is related to class, trait, interface, constant, function and variable names.

❌

class EM
{
    // ...
}

👍

class EntityMailer
{
    // ...
}

Apply in CLI?

--sniffs=ObjectCalisthenics.NamingConventions.ElementNameMinimalLength

🔧 Configurable

• in CodeSniffer XML
• in EasyCodingStandard NEON

---

7. Keep Your Classes Small

❌

class SimpleStartupController
{
    // 300 lines of code
}

👍

class SimpleStartupController
{
    // 50 lines of code
}

❌

class SomeClass
{
    public function simpleLogic()
    {
        // 30 lines of code
    }
}

👍

class SomeClass
{
    public function simpleLogic()
    {
        // 10 lines of code
    }
}

❌

class SomeClass
{
    // 20 properties
}

👍

class SomeClass
{
    // 5 properties
}

❌

class SomeClass
{
    // 20 methods
}

👍

class SomeClass
{
    // 5 methods
}

Apply in CLI?

--sniffs=ObjectCalisthenics.Files.ClassTraitAndInterfaceLength,ObjectCalisthenics.Files.FunctionLengthSniff,ObjectCalisthenics.Metrics.MethodPerClassLimit,ObjectCalisthenics.Metrics.PropertyPerClassLimitSniff

🔧 Configurable

• in CodeSniffer XML
• in EasyCodingStandard NEON

---

9. Do not Use Getters and Setters

This rules is partially related to Domain Driven Design.

• Classes should not contain public properties.
• Method should represent behavior, not set values.

❌

class ImmutableBankAccount
{
    public $currency = 'USD';

    private $amount;

    public function setAmount(int $amount)
    {
        $this->amount = $amount;
    }
}

👍

class ImmutableBankAccount
{
    private $currency = 'USD';

    private $amount;

    public function withdrawAmount(int $withdrawnAmount)
    {
        $this->amount -= $withdrawnAmount;
    }
}

Apply in CLI?

--sniffs=ObjectCalisthenics.Classes.ForbiddenPublicProperty,ObjectCalisthenics.NamingConventions.NoSetter

---

Not Implemented Rules - Too Strict, Vague or Annoying

While using in practise, we found these rule to be too strict, vague or even annoying, rather then helping to write cleaner and more pragmatic code. They're also closely related with Domain Driven Design.

3. Wrap Primitive Types and Strings - Since PHP 7, you can use define(strict_types=1) and scalar type hints. For other cases, e.g. email, you can deal with that in your Domain via Value Objects.

4. Use First Class Collections - This rule makes sense, yet is too strict to be useful in practise. Even our code didn't pass it at all.

8. Do Not Use Classes With More Than Two Instance Variables - This depends on individual domain of each project. It doesn't make sense to make a rule for that.

---

3 Rules for Contributing

• 1 feature per PR

• every new feature must be covered by tests

• all tests and style checks must pass

  composer complete-check

We will be happy to merge your feature then.