diig_run_06.go

type fileReader struct {
    src string
}

func (f *fileReader) Read() ([]byte, error) {
    return ioutil.ReadFile(f.src)
}

type dbReader struct {
    host  string
    query string
}

func (d *dbReader) Read() ([]byte, error) {
    return []byte("query db: host[%s], query[%s]", d.host, d.query)
}

fr := &fileReader{
    src: "/a/b/c",
}

dbr := &dbReader{
    host:  "127.0.0.1",
    query: "q",
}

// case file reader
e.Run(fr, ...)

// case database reader
e.Run(dbr, ...)