Joose (framework)

Joose is a meta-object system for JavaScript. It provides a way to build JavaScript applications using object-oriented principles and design patterns similar to those found in languages like Perl, Python, and Smalltalk. Joose aims to address limitations in JavaScript's native object model by adding features such as class-based inheritance, roles (mixins), attributes with automatic accessors, and method modifiers.

Joose differs from classical JavaScript prototyping by introducing explicit class definitions and a metaclass system. This allows developers to define classes with attributes, methods, and relationships in a declarative style. The metaclass system provides mechanisms for managing class creation, inheritance, and object instantiation.

Key features of Joose include:

• Class-based object orientation: Defines classes using the Class keyword, enabling familiar object-oriented concepts.
• Roles (Mixins): Allows classes to compose functionality from multiple roles, providing a flexible mechanism for code reuse. Roles provide a way to add behavior to a class without creating complex inheritance hierarchies.
• Attributes: Provides a declarative way to define object attributes, including type constraints, default values, and automatic accessor/mutator methods.
• Method modifiers: Offers before, after, and around method modifiers, enabling the modification of method behavior without directly altering the original method's code. This promotes the separation of concerns and allows for aspect-oriented programming techniques.
• Meta-object protocol (MOP): Exposes the underlying structure of classes and objects, enabling introspection and dynamic modification of object behavior.
• Introspection: Provides mechanisms to inspect classes and objects at runtime, including accessing attributes, methods, and roles.
• Dependency management: Helps manage dependencies between classes and modules.

Joose was designed to make it easier to build large, complex JavaScript applications by providing a more structured and maintainable object-oriented development environment. While popular for a period, its usage has declined as native JavaScript features such as ES6 classes and modules have become more widely adopted and supported by browsers. Some of Joose's concepts have influenced other JavaScript libraries and frameworks.