Does it make sense to have two packages in the same directory?
GoPackageGo Problem Overview
I have a project that provides a library (exports some funcs) and also must provide a command-line interface (there must be an executable file).
Example of directory structure:
whatever.io/
myproject/
main.go
myproject.go
The go compiler needs the package main and func main to start execution. My library needs the package myproject where I put stuff on it. This is what the go tool says when I am building another project that tries to import myproject:
main.go:5:2: found packages myproject (myproject.go) and main (main.go) in $GOPATH/src/whatever.io/myproject
So I believe there is no way to do it.
Should I move the library or the CLI to another package?
Go Solutions
Solution 1 - Go
Just move your packages inside a new folder within the same directory of main.go. Remember to import the new package from the reference of the $GOPATH.
Example:
user@user:~/p/go/test/so-multipack$ ls -R
.:
a main.go
./a:
a.go
user@user:~/p/go/test/so-multipack$ cat main.go
package main
import (
"../so-multipack/a"
)
func main(){
a.Hello()
}
user@user:~/p/go/test/so-multipack$ cat a/a.go
package a
import (
"fmt"
)
func Hello(){
fmt.Println("hello from a")
}
user@user:~/p/go/test/so-multipack$ go run main.go
hello from a
user@user:~/p/go/test/so-multipack$ go build
user@user:~/p/go/test/so-multipack$ ls
a main.go so-multipack
user@user:~/p/go/test/so-multipack$
Useful link:
https://stackoverflow.com/questions/19234445/go-build-vs-go-build-file-go/19240125#19240125
Solution 2 - Go
You cannot have two packages per directory, hence the error. So the solution as @Larry Battle said to move your myproject.go
to a new directory.
From How to write go code
> Go code must be kept inside a workspace. A workspace is a directory > hierarchy with three directories at its root: > > src contains Go source files organized into packages (one package per directory), > > pkg contains package objects, and > > bin contains executable commands.
Solution 3 - Go
In most cases, no. However, there is an exception for unit tests.
Working Example:
Here are 2 different packages (mypackage
and mypackage_test
) in 1 directory (mypackage
). The compiler will not complain about this.
mypackage folder:
mypackage/
foo.go
foo_test.go
mypackage/foo.go:
package mypackage
func Add(a int, b int) int {
return a + b
}
mypackage/foo_test.go:
package mypackage_test
// Unit tests...
Rules:
- The 2 packages must have the following names:
- NameOfDirectory.
- NameOfDirectory +
_test
.
- The names of the files in the
_test
package must end with_test.go
If you're receiving a confusing compiler error along the lines of found packages "foo" and "bar"
, you've probably broken one or more of these rules.
Solution 4 - Go
You can't have two golang files in one directory with two packages. So you need to move main.go
out of myproject
.
the directory structure before move
whatever.io/
go.mod
myproject/
main.go
myproject.go
After move
whatever.io/
go.mod
main.go
myproject/
myproject.go
And you need to change your main.go
's import path. If the module name is aaa
Before
import "aaa"
Need change to this
import "aaa/myproject"