How to pass a variable in a Golang callback function?

Question

I have the following code:

func loopThroughDirs(path string, fileInfo os.FileInfo, err error) error {
    ...do something with service...
    return nil
}

func main() {
    service, err := storage.New(client)
    ...
    filepath.Walk(*dirName, loopThroughDirs)
}

The problem I want to solve is this, I want to use service inside loopThroughDirs(). How do I do this?

PS: Is the loopThroughDirs function inside filepath.Walk() called a callback in Go?

Answer 1

You can also try returning a WalkFuncfunction :

func main() {
    service, err := storage.New(client)
    ...
    filepath.Walk(*dirName, getWalkFunc(service))
}

func getWalkFunc(service storage.Service) filepath.WalkFunc {
    return func(path string, fileInfo os.FileInfo, err error) error {
        // ...do something with service...
        return nil
    }
}