How to have a global variable accessible across all packages

Question

I have a main.go file which has:

// running the router in port 9000 func main() {     router,Global := routers.InitApp()     fmt.println(Global)     router.RunTLS(":9000" , "domain.crt" , "domain.key") } 

In router.InitMap I want to declare a global variable which can be accessed throughout my application anywhere. Is is possible? I tried:

func InitApp() (*gin.Engine,string) {         var Global= "myvalue"                    router := gin.New()         return router,Global   } 

But I can't access the variable Global even in the same package.

Answer 1

declare a variable at the top level - outside of any functions:

var Global = "myvalue"  func InitApp() (string) {         var Global= "myvalue"         return Global  } 

Since the name of the variable starts with an uppercase letter, the variable will be available both in the current package through its name - and in any other package when you import the package defining the variable and qualify it with the package name as in: return packagename.Global.

Here's another illustration (also in the Go playground: https://play.golang.org/p/h2iVjM6Fpk):

package main  import (     "fmt" )  var greeting = "Hello, world!"  func main() {     fmt.Println(greeting) } 

See also Go Tour: "Variables" https://tour.golang.org/basics/8 and "Exported names" https://tour.golang.org/basics/3.