Golang auto-including extensible application

Question

I am fairly new to Go and am curious if there is an established design pattern for extensible applications.

For example, in my source I have an extensions directory where I place different application specific extensions for my program. I currently load each in my main function individually by name. I would like to have the program auto-include my extensions when it gets compiled.

Just to be clear, I am not trying to dynamically load extensions at runtime. I would just like to make adding an extension to the program as simple as:

1. Drop file in extensions folder
2. Recompile

If this is just not possible with Go then I'll make due, but I'm just thinking there has to be a better way to do this.

To show more clearly what I want to make simpler, here is an example of what I do now:

main.go

package main

import (
    "github.com/go-martini/martini"
    "gopath/project/extensions"
)

func main() {
    app := martini.Classic()

    // Enable Each Extension
    app.Router.Group("/example", extensions.Example)
 // app.Router.Group("/example2", extensions.Example2)
 // ...


    app.Run()
}

extensions/example.go

package extensions

import (
    "github.com/codegangsta/martini-contrib/render"
    "github.com/go-martini/martini"
)

func Example(router martini.Router) {
    router.Get("", func(r render.Render) {
        // respond to query
        r.JSON(200, "")
    })
}

Answer 1

Use an init method in each extension go file to register the extension.

So in plugin1.go you'd write

func init() {
    App.Router.Group("/example", extensions.Example)
}

You'd need to make app public.

You could use a registration function in the main code instead.

I use this technique in rclone: Here is the registration function and here is an example of it being called. The modules are each compiled in by including them in the main pacakge