Strategy Pattern Generator

Creates Strategy pattern infrastructure for interchangeable algorithm families.

When to Use

| Scenario | Example | |----------|---------| | Multiple algorithms | Pricing, tax, shipping calculation | | Runtime selection | Payment processing based on amount | | Avoiding conditionals | Replace switch/if-else chains | | Algorithm families | Sorting, compression, encryption |

Component Characteristics

StrategyInterface

• Defines algorithm contract
• Single method for execution
• Supports method for selection

Strategy Resolver

• Resolves appropriate strategy
• Based on input criteria
• Falls back to default

Concrete Strategies

• Implement specific algorithms
• Interchangeable via interface
• Encapsulate algorithm details

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Generation Process

Step 1: Generate Strategy Interface

Path: src/Domain/{BoundedContext}/Strategy/

1. {Name}StrategyInterface.php — Algorithm contract with supports method

Step 2: Generate Concrete Strategies

Path: src/Domain/{BoundedContext}/Strategy/

1. {Variant1}{Name}Strategy.php — First algorithm implementation
2. {Variant2}{Name}Strategy.php — Second algorithm implementation
3. Default{Name}Strategy.php — Fallback implementation

Step 3: Generate Resolver

Path: src/Domain/{BoundedContext}/Strategy/

1. {Name}StrategyResolver.php — Strategy selection logic

Step 4: Generate Service (Optional)

Path: src/Domain/{BoundedContext}/Strategy/

1. {Name}Service.php — Facade using resolver

Step 5: Generate Tests

1. {Variant}{Name}StrategyTest.php — Individual strategy tests
2. {Name}StrategyResolverTest.php — Resolver tests

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File Placement

| Component | Path | |-----------|------| | Strategy Interface | src/Domain/{BoundedContext}/Strategy/ | | Concrete Strategies | src/Domain/{BoundedContext}/Strategy/ | | Resolver | src/Domain/{BoundedContext}/Strategy/ | | Unit Tests | tests/Unit/Domain/{BoundedContext}/Strategy/ |

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Naming Conventions

| Component | Pattern | Example | |-----------|---------|---------| | Interface | {Name}StrategyInterface | PricingStrategyInterface | | Concrete | {Variant}{Name}Strategy | BulkPricingStrategy | | Context | {Name}Context | PricingContext | | Resolver | {Name}StrategyResolver | PricingStrategyResolver | | Test | {ClassName}Test | BulkPricingStrategyTest |

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Quick Template Reference

Strategy Interface

interface {Name}StrategyInterface
{
    public function execute({InputType} $input): {OutputType};
    public function supports({InputType} $input): bool;
}

Concrete Strategy

final readonly class {Variant}{Name}Strategy implements {Name}StrategyInterface
{
    public function execute({InputType} $input): {OutputType}
    {
        {algorithmImplementation}
    }

    public function supports({InputType} $input): bool
    {
        return {condition};
    }
}

Strategy Resolver

final readonly class {Name}StrategyResolver
{
    public function __construct(
        private iterable $strategies,
        private {Name}StrategyInterface $defaultStrategy
    ) {}

    public function resolve({InputType} $input): {Name}StrategyInterface
    {
        foreach ($this->strategies as $strategy) {
            if ($strategy->supports($input)) {
                return $strategy;
            }
        }
        return $this->defaultStrategy;
    }
}

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Usage Example

// Configure strategies
$resolver = new PricingStrategyResolver(
    strategies: [
        new BulkPricingStrategy(),      // 15% off for 100+ items
        new PromotionalPricingStrategy(), // Active promotion discount
        new VipPricingStrategy(),        // VIP customer discount
    ],
    defaultStrategy: new RegularPricingStrategy()
);

// Use in service
$strategy = $resolver->resolve($pricingContext);
$price = $strategy->calculatePrice($pricingContext);

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Common Strategy Examples

| Domain | Strategies | |--------|------------| | Pricing | Regular, Bulk, Promotional, VIP | | Shipping | Standard, Express, Free, International | | Tax | US, EU, Exempt, Zero-rated | | Payment | Credit Card, PayPal, Bank Transfer | | Discount | Percentage, Fixed, Buy-One-Get-One |

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Anti-patterns to Avoid

| Anti-pattern | Problem | Solution | |--------------|---------|----------| | Stateful Strategies | Side effects | Make strategies readonly | | Fat Context | Too much coupling | Minimal context interface | | Missing Resolver | Manual strategy selection | Use resolver pattern | | Over-engineering | Single algorithm | Don't use pattern | | Leaky Abstraction | Strategy-specific types | Use shared interfaces |

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References

For complete PHP templates and examples, see:

• references/templates.md — Strategy Interface, Concrete Strategy, Resolver, Context templates
• references/examples.md — Pricing, Shipping, Tax strategies and tests