In Go, how to call variables defined in main.go files in non-main.go files?

Best practices for accessing variables across packages in Go

In Go, it is not best practice to define global variables directly in main.go file and access directly in other files. A better approach is to use Go's package management mechanism to define variables in separate packages and initialize them in main functions.

Question: How to access variables defined in main.go file in a file that is not main package?

Solution: define variables in separate packages.

step:

1. Create a standalone package (for example: config ) : Create a new Go package, such as config , and define the variables that need to be shared. For example, in config/config.go file:

 package config

import (
    "time"
)

var StartTime int64

2. Initialize variables in main function : In main.go file, import config package and initialize the StartTime variable in main function:

 package main

import (
    "fmt"
    "path/to/config" // Replace path/to for your config package path)

func main() {
    config.StartTime = time.Now().Unix()
    fmt.Println("Application started at:", config.StartTime)
    // ... your main logic ...
}

3. Access variables in other packages : In other Go files that need to use StartTime variables, import config package and access directly:

 package other

import (
    "fmt"
    "path/to/config" // Replace path/to for your config package path)

func MyFunction() {
    fmt.Println("Application started at (from other package):", config.StartTime)
}

explain:

This method avoids direct dependence on main packages and improves the reusability and maintainability of the code. Each package has its own independent scope, and in this way we can safely share data between different packages without naming conflicts or unexpected modifications. _ "path/to/config" is used to initialize packages, even if nothing in the package is used directly.

This way, you can access StartTime variables in any other Go file, and the code structure is clearer and easy to maintain and expand. Remember to replace "path/to/config" for the path to your actual config package.

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