The blog post advocates for a layered approach to structuring Go applications, emphasizing separation of concerns and dependency inversion. It proposes organizing code into distinct layers – domain, service, handler – with each layer depending only on the layers beneath it. The domain layer houses core business logic and entities, the service layer orchestrates domain operations and handles application-specific logic, and the handler layer interacts with external systems like databases and HTTP requests. This layered structure promotes testability, maintainability, and clearer understanding of the codebase by enforcing boundaries and reducing dependencies between different parts of the application. This approach differs from strictly hexagonal architecture, allowing the service layer to orchestrate domain logic, and focuses on practical application over strict adherence to architectural patterns.
Go 1.21 introduces a new mechanism for building more modular and extensible WebAssembly applications. Previously, interacting with JavaScript from Go WASM required compiling all the code into a single, large WASM module. Now, developers can compile Go functions as individual WASM modules and dynamically import and export them using JavaScript's standard module loading system. This allows for creating smaller initial downloads, lazy-loading functionalities, and sharing Go-defined APIs with JavaScript, facilitating the development of more complex and dynamic web applications. This also enables developers to build extensions for existing WASM applications written in other languages, fostering a more interconnected and collaborative WASM ecosystem.
HN commenters generally expressed excitement about Go's new Wasm capabilities, particularly the ability to import and export functions, enabling more dynamic and extensible Wasm applications. Several highlighted the potential for creating plugins and modules with Go, simplifying development and deployment compared to current WebAssembly workflows. Some discussed the implications for server-side Wasm and potential performance benefits. A few users raised questions about garbage collection and memory management with this new functionality, and another thread explored comparisons to JavaScript's module system and the potential for better tooling around Wasm. Some expressed concerns about whether it's better to use Go or Rust for Wasm development, and there was an insightful dialogue comparing wasmexport with previous approaches.
Russ Cox's "Go Data Structures: Interfaces" explains how Go's interfaces are implemented efficiently. Unlike languages with vtables (virtual method tables) associated with objects, Go uses interface tables (itabs) associated with the interface itself. When an interface variable holds a concrete type, the itab links the interface's methods to the concrete type's corresponding methods. This approach allows for efficient lookups and avoids the overhead of storing method pointers within every object. Furthermore, Go supports implicit interface satisfaction, meaning types don't explicitly declare they implement an interface. This contributes to decoupled and flexible code. The article demonstrates this through examples of common data structures like stacks and sorted maps, showcasing how interfaces enable code reuse and extensibility without sacrificing performance.
HN commenters largely praise Russ Cox's clear explanation of Go's interfaces, particularly how they differ from and improve upon traditional object-oriented approaches. Several highlight the elegance and simplicity of Go's implicit interface satisfaction, contrasting it with the verbosity of explicit declarations like those in Java or C#. Some discuss the performance implications of interface calls, with one noting the potential cost of indirect calls, though another points out that Go's compiler effectively optimizes many of these. A few comments delve into more specific aspects of interface design, like the distinction between value and pointer receivers and the use of the empty interface. Overall, there's a strong sense of appreciation for the article's clarity and the design of Go's interface system.
Go's type parameters, introduced in 1.18, allow generic programming but lack the expressiveness of interface constraints found in other languages. Instead of directly specifying the required methods of a type parameter, Go uses interfaces that list concrete types satisfying the desired constraint. This approach, while functional, can be verbose, especially for common constraints like "any integer" or "any ordered type." The constraints package offers pre-defined interfaces for various common use cases, reducing boilerplate and improving code readability. However, creating custom constraints for more complex scenarios still involves defining interfaces with type lists, leading to potential maintenance issues as new types are introduced. The article explores these limitations and proposes potential future directions for Go's type constraints, including the possibility of supporting type sets defined by logical expressions over existing types and interfaces.
Hacker News users generally praised the article for its clear explanation of constraints in Go, particularly for newcomers. Several commenters appreciated the author's approach of starting with an intuitive example before diving into the technical details. Some pointed out the connection between Go's constraints and type classes in Haskell, while others discussed the potential downsides, such as increased compile times and the verbosity of constraint declarations. One commenter suggested exploring alternatives like Go's built-in sort.Interface for simpler cases, and another offered a more concise way to define constraints using type aliases. The practical applications of constraints were also highlighted, particularly in scenarios involving generic data structures and algorithms.
Summary of Comments ( 16 )
https://news.ycombinator.com/item?id=43740992
Hacker News users generally praised the article for its clear explanation of layered architecture in Go, particularly appreciating the focus on dependency inversion and the practical "domain" layer example. Some debated the merits of layered architecture in general, with a few suggesting alternative approaches like hexagonal architecture or Clean Architecture, noting potential drawbacks like increased boilerplate. A recurring theme was the importance of considering the project's complexity before adopting a layered approach, with simpler projects potentially not needing such strict structure. Others shared related experiences and alternative approaches to organizing Go code, highlighting the "package by feature" method and discussing the challenges of maintaining large, complex codebases. Several commenters also appreciated the author's clear and concise writing style.
The Hacker News post titled "Layered Design in Go" (linking to an article about the same topic) generated several comments discussing the merits and drawbacks of the layered architecture approach in Go, along with alternative suggestions and experiences.
Several commenters appreciate the clarity and simplicity presented in the article. One user found the article a helpful reminder of good software engineering principles, applicable beyond just Go. Another agreed with the author's focus on dependency inversion, highlighting its crucial role in building testable and maintainable software. The conciseness of the article was also praised.
A recurring theme in the comments is the discussion of alternative approaches to layered architecture, particularly hexagonal architecture (also known as ports and adapters). Commenters pointed out the benefits of hexagonal architecture in terms of decoupling business logic from external dependencies, ultimately improving testability and flexibility. Some argued that while layered architecture might be suitable for simpler projects, hexagonal architecture offers greater advantages for more complex applications.
A few comments also delved into the specifics of dependency injection in Go. One commenter suggested using a "wire" tool for compile-time dependency injection, while others discussed the pros and cons of using interfaces for dependency injection. A point was raised about the potential overhead of interfaces in Go and the consideration of using concrete types for dependencies in performance-sensitive scenarios.
The discussion also touched upon the trade-offs between strict layering and practicality. One commenter argued that rigid adherence to layered architecture can sometimes lead to unnecessary abstraction and complexity. The idea of allowing some controlled violation of layering for pragmatic reasons was also proposed.
A few commenters shared their own experiences with layered and hexagonal architectures, offering real-world examples of where each approach proved beneficial. These anecdotal comments provided valuable context to the more theoretical discussions.
Overall, the comments on Hacker News presented a balanced view of layered architecture in Go. While acknowledging its simplicity and usefulness in certain contexts, the commenters also highlighted potential limitations and explored alternative architectural patterns like hexagonal architecture. The discussion was constructive and insightful, offering practical advice and diverse perspectives on software design in Go.