Organizing Code in Multi-Package Projects

In Go projects that require both a library and a command-line interface (CLI), it is common to encounter the issue of having multiple packages in the same directory.

One such project structure:

whatever.io/
    myproject/
        main.go
        myproject.go

The package main and func main are essential for initiating execution in Go, while a library requires a separate package, such as package myproject. However, when importing this project, the Go compiler may object:

main.go:5:2: found packages myproject (myproject.go) and main (main.go) in $GOPATH/src/whatever.io/myproject

Solution: Nested Packages

To resolve this issue, place both packages within a new folder inside the same directory as main.go. Remember to update the import statements to reference the new package from your $GOPATH.

For example:

whatever.io/
    myproject/
        library/
            myproject.go
        main.go

In main.go, import the library package as follows:

import "../library/myproject"

This approach ensures a clear separation between the library and CLI while allowing both to reside in the same directory.

Additional Notes

• Moving packages into a nested structure does not affect the functionality of either package.
• go run and go build commands can be used to test and build the project.
• Refer to the provided link for further details on the differences between go build file.go and go build.