Design Patterns Pokedex (Rust)

This is a work-in-progress, many many design changes still to be worked on as well as more patterns to be included.

Classic software design patterns case study, modeled through a Pokémon-inspired Pokedex.
Each module demonstrates how a different pattern can be implemented using idiomatic Rust features such as traits, ownership, and type safety.

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Overview

This project explores the following design patterns:

Pattern	File	Concept Demonstrated
Factory	bin/factory.rs	Centralized object creation logic (PokemonFactory)
Decorator	bin/decorator.rs	Adds behavior dynamically to existing objects (AttackAnalyser)
Singleton	bin/singleton.rs	Single shared instance across the app (PokeDex)
Strategy	bin/strategy.rs	Dynamic behavior selection (Damage calculation)

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Project Structure

pokerust/
├── src/
├── └── bin/
    │   ├── factory.rs      # Factory Pattern example
    │   ├── decorator.rs    # Decorator Pattern example
    │   ├── singleton.rs    # Singleton Pattern example
    │   └── strategy.rs     # Strategy Pattern example
    │   └── lib.rs          # Core module with Pokemon definitions and behavior
└── Cargo.toml

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Running Examples

Each design pattern can be executed separately:

Factory

cargo run --bin factory

Decorator

cargo run --bin decorator

Singleton

cargo run --bin singleton

Strategy

cargo run --bin strategy

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Core Concepts

• Traits as Interfaces: All Pokémon share common behavior via the PokemonActions trait.
• Ownership and Lifetimes: Each Pokémon carries its own data safely across examples.
• Generics and Dynamic Dispatch: Patterns like Strategy and Decorator leverage trait objects (dyn Trait) for runtime polymorphism.
• Safe Concurrency: The Singleton uses OnceLock for safe, lazily-initialized global state.

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Example – Factory Pattern

let charmander = PokemonFactory::new_pokemon(PokemonType::Fire);
charmander.fight();

Output:

Pokemon attacked with Blaze!

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Example – Strategy Pattern

let fire_strategy = Box::new(FireDamage);
let context = PokemonStrategyContext::new(fire_strategy);
context.process_strategy(squirtle);