golang-uber-dig

The golang-uber-dig skill provides expert guidance for implementing dependency injection in Go applications using the uber-go/dig library. This reflection-based container manages object graphs at application startup, enabling developers to wire complex service dependencies without manual instantiation. The skill helps teams adopt dig's core primitives including Provide/Invoke patterns, parameter and result objects using dig.In/dig.Out, and advanced features like named values, value groups, optional dependencies, scopes, and decorators.

The skill covers dig's lazy and memoized constructor system where each type is built once and shared as a singleton per container. It explains how to structure constructors following the "accept interfaces, return structs" principle, use parameter objects to manage functions with multiple dependencies, leverage named values and value groups for disambiguation, handle optional dependencies gracefully, and apply decorators to modify provided values. The skill also clarifies the relationship between dig and fx, helping developers choose the appropriate tool based on whether they need just dependency injection or a full application framework with lifecycle management.

This skill targets Go architects and backend engineers building services with complex dependency graphs, particularly those migrating to or already using uber-go/dig. It's especially valuable when wiring application composition roots, building CLI tools or libraries that expose a DI container, creating test harnesses, or embedding dependency injection into existing applications. The skill ensures developers follow best practices like keeping the container at the composition root, depending on interfaces rather than concrete types, and treating constructor errors as first-class failures.