Golang，Go：具有返回接口的映射？

Question

http://golang.org/pkg/sort/

This is from Go example.

 // OrderedBy returns a Sorter that sorts using the less functions, in order.
// Call its Sort method to sort the data.
func OrderedBy(less ...lessFunc) *multiSorter {
    return &multiSorter{
        changes: changes,
        less:    less,
    }
}

What does this do by colon? Is it mapping? Is it closure? Too much new syntax here. What should I read to understand this syntax in Go?

Answer 1

It's a factory function, creating and initialising a struct of type multisorter:

https://sites.google.com/site/gopatterns/object-oriented/constructors

Additionally, Go "constructors" can be written succinctly using initializers within a factory function:

function NewMatrix(rows, cols, int) *matrix {
    return &matrix{rows, cols, make([]float, rows*cols)}
}

Also, it is using named parameters when initialising:

http://www.golang-book.com/9

This allocates memory for all the fields, sets each of them to their zero value and returns a pointer. (Circle) More often we want to give each of the fields a value. We can do this in two ways. Like this:

c := Circle{x: 0, y: 0, r: 5}