Hands-On Dependency Injection in Go

A long constructor parameter list

A long constructor parameter list is perhaps the most common and most often complained about code damage caused by DI. While DI is not the root cause of code damage, it certainly doesn't help. 

Consider the following example, which uses constructor injection:

func NewMyHandler(logger Logger, stats Instrumentation,   parser Parser, formatter Formatter,   limiter RateLimiter,   cache Cache, db Datastore) *MyHandler {   return &MyHandler{      // code removed   }}// MyHandler does something fantastictype MyHandler struct {   // code removed}func (m *MyHandler) ServeHTTP(response http.ResponseWriter, request *http.Request) {   // code removed}

The constructor simply has too many parameters. This makes it unwieldy to use, test, ...