Template Method Pattern Generator

Creates Template Method pattern infrastructure for algorithm skeletons with customizable steps.

When to Use

| Scenario | Example | |----------|---------| | Common algorithm structure | Data import/export with format variations | | Controlled extension points | Report generation with customizable sections | | Code reuse across variants | Order processing with type-specific steps | | Invariant parts protection | Template rendering with hooks |

Component Characteristics

Abstract Template Class

• Defines algorithm skeleton
• Implements invariant steps
• Declares abstract/hook methods
• Calls methods in sequence

Concrete Implementations

• Override specific steps
• Provide algorithm variants
• Inherit common behavior
• Maintain overall structure

Hook Methods

• Optional override points
• Default empty implementation
• Allow customization
• Don't break flow

---

Generation Process

Step 1: Generate Abstract Template

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

1. Abstract{Name}Template.php — Algorithm skeleton with template method

Step 2: Generate Concrete Templates

Path: src/Domain/{BoundedContext}/Template/ or src/Application/{BoundedContext}/

1. {Variant1}{Name}Template.php — First variant implementation
2. {Variant2}{Name}Template.php — Second variant implementation
3. {Variant3}{Name}Template.php — Third variant implementation

Step 3: Generate Support Classes (Optional)

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

1. {Name}Result.php — Result value object
2. {Name}Config.php — Configuration value object

Step 4: Generate Tests

1. {Variant}{Name}TemplateTest.php — Individual template tests
2. Abstract{Name}TemplateTest.php — Template skeleton tests

---

File Placement

| Component | Path | |-----------|------| | Abstract Template | src/Domain/{BoundedContext}/Template/ | | Concrete Templates (Domain logic) | src/Domain/{BoundedContext}/Template/ | | Concrete Templates (App logic) | src/Application/{BoundedContext}/ | | Unit Tests | tests/Unit/Domain/{BoundedContext}/Template/ |

---

Naming Conventions

| Component | Pattern | Example | |-----------|---------|---------| | Abstract | Abstract{Name}Template | AbstractDataImporterTemplate | | Concrete | {Variant}{Name}Template | CsvDataImporterTemplate | | Template Method | execute() or process() | execute() | | Hook Method | before{Step}(), after{Step}() | beforeValidation() | | Test | {ClassName}Test | CsvDataImporterTemplateTest |

---

Quick Template Reference

Abstract Template

abstract readonly class Abstract{Name}Template
{
    public function execute({InputType} $input): {OutputType}
    {
        $this->validate($input);
        $data = $this->extract($input);
        $transformed = $this->transform($data);
        $result = $this->load($transformed);
        $this->afterLoad($result);

        return $result;
    }

    abstract protected function extract({InputType} $input): array;
    abstract protected function transform(array $data): array;

    protected function validate({InputType} $input): void
    {
        // Default validation
    }

    protected function afterLoad({OutputType} $result): void
    {
        // Hook method - optional override
    }
}

Concrete Template

final readonly class {Variant}{Name}Template extends Abstract{Name}Template
{
    protected function extract({InputType} $input): array
    {
        // Variant-specific extraction
    }

    protected function transform(array $data): array
    {
        // Variant-specific transformation
    }
}

---

Usage Example

// Create templates for different formats
$csvImporter = new CsvDataImporterTemplate();
$jsonImporter = new JsonDataImporterTemplate();
$xmlImporter = new XmlDataImporterTemplate();

// Use same interface
$result = $csvImporter->execute($fileContent);

---

Common Template Method Variants

| Domain | Variants | |--------|----------| | Data Import | CSV, JSON, XML, Excel | | Report Generation | PDF, Excel, HTML, Email | | Order Processing | Standard, Express, International | | Document Rendering | Markdown, LaTeX, HTML | | Payment Flow | Card, Bank Transfer, Digital Wallet |

---

Anti-patterns to Avoid

| Anti-pattern | Problem | Solution | |--------------|---------|----------| | Too many abstract methods | Hard to implement | Use hook methods with defaults | | Public template steps | Breaks encapsulation | Make steps protected/private | | Mutable state | Side effects | Use readonly classes, pass data | | Deep inheritance | Complexity | Limit to 2-3 levels max | | Breaking LSP | Inconsistent behavior | Maintain contract in overrides |

---

References

For complete PHP templates and examples, see:

• references/templates.md — Abstract Template, Concrete Template, Hook Methods templates
• references/examples.md — DataImporter, ReportGenerator, OrderProcessor with tests