This branch refactors the Command interface.

cmd/juju/addrelation.go

 package main
 
 import (
         "fmt"
         "launchpad.net/gnuflag"
         "launchpad.net/juju-core/cmd"
         "launchpad.net/juju-core/juju"
 )
 
 // AddRelationCommand adds relations between service endpoints.
 type AddRelationCommand struct {
         EnvName   string
         Endpoints []string
 }
 
 func (c *AddRelationCommand) Info() *cmd.Info {
         return &cmd.Info{
                 "add-relation", "<service1>[:<relation name1>] <service2>[:<relation name2>]",
                 "add a relation between two services", "",
         }
 }
 
-func (c *AddRelationCommand) Init(f *gnuflag.FlagSet, args []string) error {
+func (c *AddRelationCommand) SetFlags(f *gnuflag.FlagSet) {
         addEnvironFlags(&c.EnvName, f)
-        if err := f.Parse(true, args); err != nil {
-                return err
-        }
-        args = f.Args()
+}
+
+func (c *AddRelationCommand) Init(args []string) error {
         if len(args) != 2 {
                 return fmt.Errorf("a relation must involve two services")
         }
         c.Endpoints = args
         return nil
 }
 
 func (c *AddRelationCommand) Run(_ *cmd.Context) error {
         conn, err := juju.NewConnFromName(c.EnvName)
         if err != nil {
                 return err
         }
         defer conn.Close()
         eps, err := conn.State.InferEndpoints(c.Endpoints)
         if err != nil {
                 return err
         }
         _, err = conn.State.AddRelation(eps...)
         return err
 }