What's the correct organisation for Go projects using Git (or any VCS)?

Question

My GOPATH is /Users/joe/go. I am working on a project called myproj, which is a package called myproj.

If I want to be able to write import "myproj" then the directory structure I need is:

$GOPATH/src/myproj/myproj.go
$GOPATH/src/myproj/myproj_test.go
...

However, I can't seem to make this fit with Git. If I look at an example package from Google I see the following format:

go.example/hello/hello.go
go.example/LICENSE

Where go.example is the name of the repo.

So the actual package directories are found inside the repository. If I put the contents of this repository in a directory on my $GOPATH, e.g.

$GOPATH/src/go.example/hello/hello.go
$GOPATH/src/go.example/LICENSE

then I will have to type import "go.example/hello" rather than import "hello".

Coming back to my project, I need to package this up in a Git repository then I need a container directory. So my current file structure is:

$GOPATH/src/myproj                        # The dir for the git repo
$GOPATH/src/myproj/.git
$GOPATH/src/myproj/LICENSE                # Files in the base of the repo
$GOPATH/src/myproj/myproj/myproj.go       # Package files in package dir
$GOPATH/src/myproj/myproj/myproj_test.go  

I need the outer myproj directory to bound the git repository and I need the inner one to be the package directory. The upshot is that I need to type import "myproj/myproj" rather than import "myproj".

How do I fix this? Do I have to add multiple $GOPATHS, one for each project I'm developing?

Thanks in advance.

Answer 1

First off:

Do I have to add multiple $GOPATHs, one for each project I'm developing?

No, you don’t need multiple $GOPATHs at all.

They are a tool for managing your (potentially several) projects. When you set up a new project environment which you already know will have some dependencies - potentially unique to that project, or which should be similiar to other peoples setups, you create a new project folder and set it as the GOPATH. That way, you can also use (= check out) specific versions of a library for that project, while using other versions for your other projects in other project folders (= GOPATHs).

As for your path issue: Go follows a generic paradigm of author/project (or organization/project). This will prevent naming clashes when several people, authors and organizations, start projects with the same names. (The author may then use sub-folders, sub-projects in “his” folder as well ofc.)

If you are aware of this and still want to use only myproj as your package path, there is no problem in creating the git repository in that folder - in contrary to the example package you linked to.

Coming back to my project, I need to package this up in a Git repository then I need a container directory.

What makes you think so then? Go does not need it. Git does neither.

So the following will work:

/src/myproj/.git
/src/myproj/myproj.go

While it is not the encouraged practice, you can put the repository into your myproj folder.

---

I tested this as follows:

FOLDER
FOLDER/src
FOLDER/src/myproj
FOLDER/src/myproj/myproj.go
FOLDER/src/mainproj
FOLDER/src/mainproj/main.go

With folder/src/myproj/myproj.go

package myproj

type My struct {
    I int
}

and folder/src/mainproj/main.go

package main

import (
    "fmt"
    "myproj"
)

func main() {
    my := myproj.My{7}
    fmt.Printf("Works! %v", my.I)
}

Running

cd FOLDER
set GOPATH=FOLDER
go run src/mainproj/main.go

will output:

Works! 7

Now, if you git init in the folder FOLDER/src/myproj, that does not matter to Go itself at all.

Answer 2

The usual setup goes like this:

$GOPATH, in the first approximation needs only one path, your example /Users/joe/go/ is just fine. Now you have a github repository myproj seen at http://github.com/joe/myproj. The import statement for this package should be

import "github.com/joe/myproj"

Looking back at your (single valued) $GOPATH, the go tool will look for your package at $GOPATH/src/github.com/joe/myproj and that's the "local" root of your "external" github repository with files myproj.go, etc.go, ... inside.

Without these conventions there will be namespace clashes with Jack's (and Alice's and Bob's) project(s) accidentally called also myproj, so I recommend to get used to this right from the beginning.

Answer 3

You'll naturally import multiple packages :

• the standard ones
• a few ones you'll download using go get
• a few ones in your project
• a few ones in other projects

The simplest is to choose a directory where you'll go get all the external packages (mysql driver for example) and add your project directories to GOPATH.

For example, here's my (simplified) GOPATH :

export GOPATH=/home/dys/dev/go:/home/dys/dev/Chrall/go:/home/dys/dev/braldop/go:/home/dys/dev/lg/go

I put all the external libraries obtained using go get in /home/dys/dev/go and Chrall, braldop and lg are 3 of my projects.

In each one of those 3 projects, I have packages and commands. For example :

/home/dys/dev/lg/go/src/pkg1/xxx.go
/home/dys/dev/lg/go/src/pkg2/xxx.go
/home/dys/dev/lg/go/src/prog1/xxx.go

etc.

All packages are found via GOPATH.

For example when I use a driver mysql, in one of those xxx.go :

import (
"database/sql"
_ "github.com/ziutek/mymysql/godrv"
)

The driver has been installed in /home/dys/dev/go using

go get github.com/ziutek/mymysql/godrv

Reference : http://golang.org/doc/code.html

GOPATH=/home/user/ext:/home/user/mygo

(On a Windows system use semicolons as the path separator instead of colons.)

Each path in the list (in this case /home/user/ext or /home/user/mygo) specifies the location of a workspace. A workspace contains Go source files and their associated package objects, and command executables.