Unpack slices on assignment?

Question

Is there an elegant way in Go to do multiple assignments from arrays like in Python? Here is a Python example of what I'm trying to do (split a string and then assign the resulting array into two variables).

python: >>> a, b = "foo;bar".split(";") 

My current solution is:

x := strings.Split("foo;bar", ";") a, b := x[0], x[1] 

I'm can see this getting messy in some constructs. The practical example I'm currently facing is a bookmark file parsing and assigning to a map:

bookmark := make(map[string]string) x := strings.Split("foo\thttps://bar", "\t") name, link := x[0], x[1] bookmark[name] = link 

Now I have a useless variable x sitting around. I'd like to do something like:

bookmark := make(map[string]string) name, line := strings.Split("foo\thttps://bar", "\t") bookmark[name] = link 

but that's invalid.

Answer 1

As Sergio Tulentsev mentioned, general packing/unpacking as is done in Python is not supported. I think the way to go there is to define your own small ad-hoc function using multiple return values:

func splitLink(s, sep string) (string, string) {     x := strings.Split(s, sep)     return x[0], x[1] } 

And you can then write:

name, link := splitLink("foo\thttps://bar", "\t") 

But this will obviously work only when at least two substrings are being split, and silently ignore if more than two were. If this is something you use a lot, it might make your code more readable though.

--EDIT--

Another way to unpack an array is via variadic pointer arguments:

func unpack(s []string, vars... *string) {     for i, str := range s {         *vars[i] = str     } } 

Which let you write:

var name, link string unpack(strings.Split("foo\thttps://bar", "\t"), &name, &link) bookmarks[name] = link 

This will work for any array size, but it is arguably less readable, and you have to declare your variables explicitly.

Answer 2

If your function is meant to split a string only by the first occurrence of the separator, you can always make your own function:

package main  import (     "fmt"     "strings" )  func Split(s, sep string) (string, string) {     // Empty string should just return empty     if len(s) == 0 {         return s, s     }         slice := strings.SplitN(s, sep, 2)      // Incase no separator was present     if len(slice) == 1 {         return slice[0], ""     }      return slice[0], slice[1] }  func main() {     a, b := Split("foo;bar;foo", ";")     fmt.Println(a, b) } 

Output:

foo bar;foo

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