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Welcome to Castlecraft Engineer Documentation

Castlecraft Engineer is a Python library providing a robust set of abstractions designed to help you implement Domain-Driven Design (DDD) building blocks in your applications. Our goal is to offer clear, testable, and maintainable components for building sophisticated software systems.

Core Philosophy

This library is built upon established software design principles, primarily:

  • Domain-Driven Design (DDD): We provide tools to model complex business domains effectively, focusing on concepts like Aggregates, Entities, Value Objects, and Repositories.
  • Command Query Responsibility Segregation (CQRS): The library encourages separating operations that change state (Commands) from operations that read state (Queries), leading to more focused and scalable components.
  • Event-Driven Architecture (EDA): Support for Domain Events allows for decoupled communication between different parts of your system and enables patterns like Event Sourcing (though full Event Sourcing is not a mandatory part of using the library).

Who Is This Library For?

Castlecraft Engineer is for Python developers who are:

  • Building applications using Domain-Driven Design principles.
  • Looking for a structured way to implement CQRS patterns.
  • Seeking to create highly testable and maintainable business logic.
  • Interested in building event-driven systems.

Key Benefits

  • Clear Abstractions: Well-defined base classes and interfaces for Aggregates, Repositories, Commands, Queries, Events, and their handlers.
  • Improved Testability: The separation of concerns and dependency injection (via punq) make components easier to test in isolation.
  • Maintainable Codebase: Promotes a structured approach to organizing business logic, leading to more understandable and maintainable code.
  • Scalability: CQRS patterns can help in scaling read and write operations independently.
  • Flexibility: While providing structure, the library is largely unopinionated about specific web frameworks or database technologies. It offers optional, integrated support for SQLModel as an ORM and Redis for caching, but these are not mandatory for using the core abstractions.

Getting Started

Ready to dive in?

  1. Installation: Head over to the Installation Guide to set up Castlecraft Engineer in your project.
  2. Quick Start: Follow our Quick Start Guide for a hands-on example of using the core components.

Documentation Sections

Explore the documentation to learn more about Castlecraft Engineer:

  • Core Concepts:
    • Aggregates
    • Repositories
    • CQRS Overview
    • Commands
    • Events
    • Event Store
    • Queries
    • Dependency Injection
    • Authorization
  • Tutorials:
    • Building a Complete Feature
  • Testing Guide: Learn how to effectively test applications built with Castlecraft Engineer using the provided testing helpers. (Testing Guide)
  • Contributing: Interested in contributing? Find out how you can help improve the library. (Contributing)
  • Changelog: See what's new in each version. (Changelog)
  • License: Understand the terms under which Castlecraft Engineer is distributed. (License)

We hope this documentation helps you effectively use Castlecraft Engineer to build amazing applications!