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.
Paul Graham's 2009 post argues that Twitter's significance stems not from its seeming triviality, but from its unique blend of messaging and public broadcast. It's a new kind of medium, distinct from email or IM, offering a low-friction way to share thoughts and information publicly. This public nature fosters a sense of ambient awareness, keeping users connected to a wider circle than traditional communication methods. Its brevity and immediacy contribute to a feeling of being "present," allowing participation in real-time events and fostering a sense of shared experience. While seemingly inconsequential updates create this presence, they also pave the way for sharing genuinely valuable information within the established network.
HN commenters discuss Paul Graham's 2009 essay on Twitter's significance. Several highlight the prescience of his observations about its future potential, particularly regarding real-time news and conversation. Some contrast Twitter's early simplicity with its current complexity, lamenting feature bloat and the rise of performative posting. Others note how Graham correctly predicted the platform's role as a powerful distribution channel, even envisioning its use for customer support. A few express skepticism about its long-term value, echoing early criticisms about the triviality of its content. Overall, the comments reflect a mix of admiration for Graham's foresight and a wistful look back at a simpler era of social media.
Summary of Comments ( 53 )
https://news.ycombinator.com/item?id=42946270
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.
The Hacker News post "Go Data Structures: Interfaces (2009)" linking to Russ Cox's blog post on Go interfaces has generated a significant discussion with 28 comments. Several commenters express appreciation for the clarity and depth of Cox's explanation, noting how it effectively illuminates the nuances of Go's interface system.
A recurring theme is the comparison of Go's interfaces to interfaces in other languages, particularly Java and C++. One commenter highlights the implicit nature of Go's interfaces, contrasting it with the explicit declarations required in Java and appreciating the resulting conciseness and flexibility. Another commenter points out the distinction between Go's compile-time interface satisfaction and Java's runtime checks, emphasizing the performance implications. The discussion also touches upon the differences in how interfaces handle inheritance and polymorphism compared to these languages. One user specifically mentions how Go's approach avoids the fragility often associated with deep inheritance hierarchies.
Several commenters delve into the practical implications of Go's interface design. One discusses the power of interfaces for decoupling and testing, facilitating the substitution of different implementations without altering dependent code. Another commenter elaborates on the efficiency of Go's interface implementation, attributing it to the use of interface tables (itab). This leads to a brief discussion about the memory layout and performance characteristics of interface values.
The conversation also explores more nuanced aspects of Go's interfaces, including the handling of nil interfaces and empty interfaces (interface{}). One commenter explains the behavior of nil interfaces and their utility in certain scenarios. Another comment thread explores the concept of empty interfaces as a form of dynamic typing within Go, along with its potential benefits and drawbacks.
A few comments offer personal anecdotes and experiences using Go interfaces. One commenter shares a positive experience using interfaces to simplify a complex codebase, highlighting the ease of adding new functionality. Another commenter reflects on the initial learning curve associated with understanding Go's implicit interfaces but ultimately appreciates the elegant design.
Finally, a couple of comments offer minor criticisms or alternative perspectives. One commenter suggests a potential improvement to the error handling related to interface conversions. Another commenter expresses a preference for explicit interface declarations, despite acknowledging the benefits of Go's implicit approach.
Overall, the comments reflect a general appreciation for the design and implementation of Go's interfaces. Commenters praise the clarity of Cox's explanation and engage in a thoughtful discussion of the practical implications, comparing and contrasting Go's approach with other languages while exploring more advanced aspects of the system.