How do I access a variable that was declared/init in my main.go in a different .go package/file? Keeps telling me that the variable is undefined (I know that global variables are bad but this is just to be used as a timestamp)
in main.go
var StartTime = time.Now()
func main(){...}
trying to access StartTime in a different .go file but keep getting StartTime undefined
I would "inject" the starttime variable instead, otherwise you have a circular dependency between the packages.
main.go
var StartTime = time.Now()
func main() {
otherPackage.StartTime = StartTime
}
otherpackage.go
var StartTime time.Time
I create a file dif.go
that contains your code:
package dif
import (
"time"
)
var StartTime = time.Now()
Outside the folder I create my main.go
, it is ok!
package main
import (
dif "./dif"
"fmt"
)
func main() {
fmt.Println(dif.StartTime)
}
Outputs:
2016-01-27 21:56:47.729019925 +0800 CST
Files directory structure:
folder
main.go
dif
dif.go
It works!
I suggest use the common way of import.
First I will explain the way it called "relative import" maybe this way cause of some error
Second I will explain the common way of import.
FIRST:
In go version >= 1.12 there is some new tips about import file and somethings changed.
1- You should put your file in another folder for example I create a file in "model" folder and the file's name is "example.go"
2- You have to use uppercase when you want to import a file!
3- Use Uppercase for variables, structures and functions that you want to import in another files
Notice: There is no way to import the main.go in another file.
file directory is:
root
|_____main.go
|_____model
|_____example.go
this is a example.go:
package model
import (
"time"
)
var StartTime = time.Now()
and this is main.go you should use uppercase when you want to import a file. "Mod" started with uppercase
package main
import (
Mod "./model"
"fmt"
)
func main() {
fmt.Println(Mod.StartTime)
}
NOTE!!!
NOTE: I don't recommend this this type of import!
SECOND:
(normal import)
the better way import file is:
your structure should be like this:
root
|_____github.com
|_________Your-account-name-in-github
| |__________Your-project-name
| |________main.go
| |________handlers
| |________models
|
|_________gorilla
|__________sessions
and this is a example:
package main
import (
"github.com/gorilla/sessions"
)
func main(){
//you can use sessions here
}
so you can import "github.com/gorilla/sessions" in every where that you want...just import it.
Source: Stackoverflow.com