Python to Go Cheatsheet | Hacker News Reader

Python to Go Cheatsheet

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34 pointstebeka7 comments

My god is go a cumbersome language. I get why the explicitly returned errors are a good thing but the complexity for parsing json surprises me

That's an artifact of it being statically typed. The data type to unmarshal into / marshal from needs to be defined somewhere. The extra stuff apart from error handling isn't required if you use a more generic type like `map[string]interface{}`.

What?

// example for unmarshalling an http request to JSON

contents, err := ioutil.Readall(req.Body)

if err != nil { return err }

req.Body.Close()

user := new(User)

if err := json.Unmarshal(contents, user); err != nil { return nil }

// do whatever you want with 'user'

Perhaps worth pointing out, pedantically, that really only the final two lines are the JSON handling — the first three lines here are reading/handling the input stream (HTTP).

Why do you have to call `req.Body.Close()`? Does Go not have RAII?

Does Go have something analogous to Rust's `try!` or `?` operator, which would turn it into (pseudocode):

    contents, err := try!(ioutil.Readall(req.Body))

Or:

    contents, err := ioutil.Readall(req.Body)?

If not, why not?

(I don't know Go)

No garbage collected language will ever have RAII, the features conflict. Go does not have RAII, but tries to fix it with "defer" [1].

As for why not, you'd have to ask the Go team. But my guess would be that as a general rule, Go does not have language feature X. It's a very, very basic language deliberately lacking pretty much every modern language feature you can think of. The pro/con is that programming in Go is very delibarete. Go programs will only ever do what you explicitly make them do, to an almost ridiculous extent. If a Go program knows how to sort a list of customers, it takes 20 lines of code to make it aware of how to sort any other record type. Especially operations minded people this is a big plus.

[1] https://blog.golang.org/defer-panic-and-recover

For those fluent in Go first, this is good as a quick Go to Python reference too. Though good as an initial quickstart, this invites programming in Go using a Python-style and vice versa. Glad that there’s at least a section on goroutines and chan.

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