MyClassargs

MyClassargs is a lightweight Python library that provides a declarative approach to defining constructor arguments for classes. It aims to reduce boilerplate by centralizing argument validation, normalization, and attribute binding in a single schema.

Core concepts include a declarative argument schema where each parameter declares its name, type, default value, and optional aliases; automatic validation and type coercion; support for distinguishing between required and optional parameters; and aliasing or renaming of arguments for backward compatibility. The library also handles nested structures, such as lists or dictionaries of typed elements, and can enforce constraints like value ranges or membership in a set.

Design and implementation typically rely on a metaclass or class decorator that generates an __init__ method at class definition time. The generated initializer validates incoming values, applies defaults, coerces types as needed, and assigns attributes. Some implementations offer optional immutability or frozen instances after construction.

Usage pattern: declare a class with an argument schema, then instantiate by passing keyword arguments that match the declared names. If a required argument is missing or a value fails validation, a descriptive exception is raised. The resulting object exposes attributes corresponding to the declared arguments.

Relation to other tools: MyClassargs sits between dataclasses and validation-focused libraries such as pydantic, offering lightweight validation without extensive schemas. It can be complementary to typing support and is often used in small projects or teaching examples. Limitations include less ecosystem maturity and potential performance overhead for very large schemas.