I'm following this tutorial, specifically exercise 8:
package main
import "fmt"
func swap(x, y string) (string, string) {
return y, x
}
func main() {
a, b := swap("hello", "world")
fmt.Println(a, b)
}
Specifically what does the := mean? Searching for Go documentation is very hard, ironically.
A short variable declaration uses the syntax:
ShortVarDecl = IdentifierList ":=" ExpressionList .
It is a shorthand for a regular variable declaration with initializer expressions but no types:
Keep on going to page 12 of the tour!
A Tour of Go
Inside a function, the := short assignment statement can be used in place of a var declaration with implicit type.
(Outside a function, every construct begins with a keyword and the := construct is not available.)
:= represents a variable, we can assign a value to a variable using :=.
According to my book on Go, it is just a short variable declaration statement exactly the same as
var s = ""
But it is more easy to declare, and the scope of it is less expansive. A := var decleration also can't have a type of interface{}. This is something that you will probably run into years later though
:= is not an operator. It is a part of the syntax of the Short variable declarations clause.
more on this: https://golang.org/ref/spec#Short_variable_declarations