Small introduction to tags in Go

This is what I like about Go. This &quot;small introduction&quot; is basically everything there is to know about struct tags.<p>Bonus, Gorethink tags [0] and how we use them at Lavaboom [1].<p>0: <a href="https:&#x2F;&#x2F;github.com&#x2F;dancannon&#x2F;gorethink#encodingdecoding-structs" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;dancannon&#x2F;gorethink#encodingdecoding-stru...</a><p>1: <a href="https:&#x2F;&#x2F;github.com&#x2F;lavab&#x2F;api&#x2F;tree&#x2F;master&#x2F;models" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;lavab&#x2F;api&#x2F;tree&#x2F;master&#x2F;models</a>

At GopherCon, Kyle Erf and Sam Helman gave a great talk about struct tags, how some people are currently using them.<p>SourceGraph did a write up that summarized it very nicely. <a href="https:&#x2F;&#x2F;sourcegraph.com&#x2F;blog&#x2F;live&#x2F;gophercon2015&#x2F;123669868275" rel="nofollow">https:&#x2F;&#x2F;sourcegraph.com&#x2F;blog&#x2F;live&#x2F;gophercon2015&#x2F;123669868275</a>

Why is this &quot;tag&quot; system considered a good feature? It seems so arbitrary. It&#x27;s used exclusively for reflective logic which should instead be done at compile-time via a macro system or a system like Template Haskell, which would generate instances like `ToJson`&#x2F;`FromJson` for a given struct. As the article mentions, Go tags are similar to Java annotations: a mis-feature motivated by the absence of a macro system.

tags are just strings. there is no spec tag whatsoever or syntax that can be validated at compile time.<p>A better solution would have been a proper annotation system that is part of the spec.

This should be handy for frameworks to do their own logic, but I would get very annoyed if I had to read code that was cluttered with tags.

&#x2F;&#x2F; VerifyPassword checks if password is valid and upgrades it if its encrypting scheme was outdated &#x2F;&#x2F; Returns isValid, wasUpdated, error<p>func (a *Account) VerifyPassword(password string) (bool, bool, error) {<p>this is why we need sum types people