strategy-factory-null-calculator

What problem does it solve?

Route variant-dependent calculation requests through a single entry point and delegate to the appropriate strategy.

Core Features & Use Cases

• Factory selects the correct strategy based on the variant and returns a concrete service, or a NullService when no suitable variant exists.
• BaseService defines the common calculation flow and guards; concrete services implement variant-specific logic.
• NullService provides a safe, non-operational fallback to avoid crashes when an unknown variant is encountered.
• Tests gate discipline ensures components (Factory, BaseService, NullService, and concrete services) have tests before implementation.

Quick Start

Call Calculator::Factory.for(entity).calculate to route to the correct strategy and gracefully handle unknown variants with a NullService.