Golang的自调用功能

Question

Could not easily find info on how to create a self-invoking func in Golang.

My end-goal is to export a map from a file, something like this:

type Foo struct {}
type Bar struct {}

var TypeMap map[interface{}]string;

func selfInvoking(){

  TypeMap = map[interface{}]string{
    Foo: "foo",
    Bar: "bar"
   }
}()

how can I go about exporting a populated map like this from a file in Go? It's basically for one-time configuration.

Using the pattern above, I will get

"unused variable TypeMap".

Answer 1

There are 3 ways to execute initialization code in GO:

• Constants
• Variables
• The init function

In your case you can use last two.

Variable:

var TypeMap = map[interface{}]string{
    Foo{}: "foo",
    Bar{}: "bar",
   }

The init function:

var TypeMap map[interface{}]string

func init(){
  TypeMap = map[interface{}]string{
    Foo: "foo",
    Bar: "bar",
   }
}

In any case be careful with initializers and do not use them for any complex or io code. Initializer are not very good for unit testing and errors handling/logging.