https://golang.org/ref/spec#Exported_identifiers
An identifier may be exported to permit access to it from another package. An identifier is exported if both:
- the first character of the identifier's name is a Unicode upper case letter (Unicode class "Lu"); and
- the identifier is declared in the package block or it is a field name or method name.
All other identifiers are not exported.
应用const，并且var 的名字第一个字符必须为大写 「capital letter」。
package foo
const VarPassed int64 = 12
使用包名+变量名
package main
import(
f "fmt"
"library/foo"
func main() {
f.Println(foo.VarPassed)
}
