A lightweight Elixir state machine library with Phoenix integration, providing a simple DSL for managing state transitions.
Machinery is a lightweight state machine library for Elixir that provides a simple DSL for declaring states and transitions. It simplifies state management in applications by offering a clean, unobtrusive layer for modeling workflows and business logic, with built-in support for Phoenix projects.
Elixir developers, particularly those building Phoenix applications, who need to manage state transitions in models like user accounts, orders, or document workflows.
Developers choose Machinery for its minimalistic design that integrates seamlessly with Elixir's functional paradigms, offering essential features like guard functions, callbacks, and persistence without imposing a heavy framework.
Elixir State machine thin layer for structs
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Declaring states and transitions uses a clean keyword-based DSL, as shown in the example where states and transitions are defined concisely in a module.
Seamlessly integrates with Phoenix and Ecto schemas, with specific instructions for adding state fields and using persist functions for database persistence.
Guard functions with pattern matching allow conditional transitions, preventing invalid changes based on business logic, demonstrated in the guard_transition example.
Supports before and after callbacks for side effects, enabling actions like notifications or data updates around transitions, with examples for each.
Users must implement their own persist function to save state changes to the database, adding boilerplate code and potential for errors if not handled correctly.
Lacks support for complex state machine patterns like hierarchical states, history states, or event sourcing, which might be necessary for sophisticated workflows.
The README does not specify how errors in callbacks are managed, risking silent failures if callbacks raise exceptions without proper error handling.