How to use interfaces in Go (2012)

When navigating unfamiliar Go codebases, it&#x27;s hard to know which types fulfill an interface. Say you have a function that takes an Animal; how do you figure out what to call it with?<p>Or to give a concrete example, say you want to do formatted output to stderr. How is one supposed to determine that os.Stderr is something that can be passed to fmt.Fprintf? Is there a better way than manually comparing method signatures?

&gt; type JavaProgrammer struct { &gt; }<p>&gt; func (j JavaProgrammer) Speak() string { &gt; return &quot;Design patterns!&quot; &gt; }<p><i>shrug</i> At least our language designers trusted our intelligence enough to implement generics.

Read this when I was first getting into Go; super helpful and a fun(ish) read for people curious about the language

Interesting. For pointers and interfaces, in this sample <a href="http:&#x2F;&#x2F;play.golang.org&#x2F;p&#x2F;Lf8nn_pcYO" rel="nofollow">http:&#x2F;&#x2F;play.golang.org&#x2F;p&#x2F;Lf8nn_pcYO</a>, `h3.Add2()` should fail as per OP said. I am sure, I am missing something important here. Please help.

The article is a pretty good intro to how to use interfaces. I think some people, especially those not familiar with the language would benefit from reading such articles and learning how to write idiomatic Go code, rather than ask for features that would allow them to write idiomatic $LANGUAGE_THEY_LIKE code.

Previously on HN:<p><a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=9320235" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=9320235</a><p>The blog post is from 2012.

&gt; func main() {<p>&gt; animals := []Animal{Dog{}, Cat{}, Llama{}, JavaProgrammer{}}<p>&gt; for _, animal := range animals {<p>&gt; fmt.Println(animal.Speak())<p>&gt; }<p>&gt; }<p>This makes my eyes hurt. In this modern age we still haven&#x27;t learned to create easy to read languages?

I don&#x27;t understand why you would share a three year old post explaining the basics of interfaces in Go.