commands-command.go

package commands

// ...

func (cmd *Command) Call(r Request, w io.Writer) error {
  // ...
  
  res := NewResponse(r, w) // pass the writer
  
  cmd.Run(...)
  
  // ...
}

commands-request.go

package commands

// ...

type Request struct {
  // ...
  
  Mode() RequestMode // json, text, whatevs
}

core-commands-pubsub.go

package commands

var PubsubSubCmd := &Command {
  // ...
  
  Run: func(req cmds.Request, res cmds.Response) {
    m := FloodsubMarshaller(req.Mode(), res) // res is an io.Writer
    sub := floodsub.Subscribe(req.GetArg("topic"))
    
    f, isFlusher := res.(http.Flusher)
    
    go func() {
      if isFlusher {
        f.Flush()
      }
  
      for {
        msg := sub.Next()
        m.Write(msg)
        if isFlusher {
          f.Flush()
        }
      }
    }()
  },
}