Get parameters through standard http.Handler about httprouter

[julienschmidt]

1. Also requires additional parsing (and allocations)
2. Allocations + a synchronization hot spot
3. Does the work twice

[bodokaiser]

The last idea I have is using type casting on *url.URL as it is done with http.Flusher:

f, ok := w.(http.Flusher)

or with the url:

url, ok := request.URL.(httprouter.URL)

if ok {
    fmt.Printf("param: %s\n", url.Param("id"))
}

This could also be hidden somehow in a helper function:

id, err := httprouter.Param(r, "id")

What do you think?