How to access global variables

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

3 Answers

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 ( ""
)
func main(){ //you can use sessions here
}

so you can import "" in every where that you want...just import it.