undefined: function (declared in another package)

Question

my project organisation looks like this :

• GOPATH
  • src
    • cvs/user/project
      • main.go
      • utils
        • utils.go

main.go looks like this :

package main

import (
  "fmt"
  "cvs/user/project/utils"
)

func main() {
   ...
   utilsDoSomething()
   ...
}

and utils.go :

package utils

import (
  "fmt"
)   

func utilsDoSomething() {
    ...
}

The compiler tells me that :

main.go imported and not used: "cvs/user/project/utils"

main.go undefined: utilsDoSomething

I don't know what I'm doing wrong. Any idea would be helpful, thank you in advance !

Answer 1

You forgot the package prefix in main.go and your function is not exported, meaning it is not accessible from other packages. To export an identifier, use a capital letter at the beginning of the name:

utils.UtilsDoSomething()

Once you have the utils prefix you can also drop the Utils in the name:

utils.DoSomething()

If you want to import everything from the utils package into the namespace of your main application do:

import . "cvs/user/project/utils"

After that you can use DoSomething directly.

Answer 2

When you are referencing a function from a package you need to reference it using the package name.Function name (with capital case).

In your case use it as:

utils.UtilsDoSomething().