pyline

Welcome to PyLine Core

PyLine Core is a lightweight, type-safe Python micro-framework designed to simplify the implementation of the Command Query Responsibility Segregation (CQRS) pattern and Pipeline Orchestration.

Why PyLine Core?

In implementation-heavy projects, logic often becomes scattered and difficult to test. PyLine Core provides a structured foundation that:

Decouples Logic: Commands and Queries are separated from their execution logic.
Enforces Type Safety: Leverages modern Python type hints and overloads for a superior developer experience.
Simplifies Orchestration: Pipelines allow you to chain operations with automatic state management.
Event-Driven Architecture: Powerful background EventBus with Publish/Subscribe support and graceful shutdown.
Maintains Leaness: Zero external runtime dependencies in the core package.

Core Concepts

Mediator Pattern

The HandlerMediator acts as a central post office. You register handlers for specific message types (Commands or Queries), and the mediator ensures they reach their destination.

Pipelines

The Pipe component allows you to define a sequence of steps. Each step can be a Command or a Query. The pipeline handles:

Context Management: A shared dictionary passed between steps.
Auto-Mapping: Context keys are automatically mapped to step parameters.
Result Collection: Results from Queries are automatically merged back into the shared context.

Event Bus (Publish/Subscribe)

The EventBus allows components to broadcast events (like UserCreatedEvent) to multiple background handlers asynchronously, decoupling side-effects from your main business logic.

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