plumbus - Turn any function into a net/http handler

A Flexible ServeMux and HandlerFunc - Use any function as a handler, as long as you implement a few interfaces to define how that function's arguments, results, and errors are mapped to the http request and response.

Arguments

Arguments must implement plumbus.FromRequest, which looks like:

type FromRequest interface {
	FromRequest(*http.Request) error
}

However, if (at most) one parameter does not implement this interface, then that parameter will be decoded from the request body as json instead, by using the standard encoding/json package (supporting other types in the future is possible).

Return Values

Return values must implement plumbus.ToResponse, which looks like:

type ToResponse interface {
	ToResponse(http.ResponseWriter) error
}

However, if (at most) one return value does not implement this interface, then that return value will be encoded to the response body as json instead, by using the standard encoding/json package (supporting other types in the future is possible).

Errors

If a function returns an error (must be the last return value), then the result will be a 500 internal server error and no additional information about the error will be shown. However, if the error also implements the plumbus.HTTPError interface then the response code will be obtained by calling error.ResponseCode(), and the response body will be obtained from calling error.Error(). The same is true for errors returned by calls to FromRequest and ToRequest. The plumbus.HTTPError interface looks like:

type HTTPError interface {
	error
	ResponseCode() int
}

Isn't Reflection too slow?

Probabaly for some uses, however you can also run the plumbus command line tool via go generate to use code generation in place of reflection and eliminate all per-request reflection. (there will still be a small amount of reflection during setup).

Routing on Methods

To route by HTTP methods, just pass a value of type plumbus.ByMethod as your handler. This type maps from HTTP methods to (flexible) handler functions.

mux := plumbus.NewServeMux()
mux.Handle("/user", &plumbus.ByMethod{
  GET: getUser,
  POST: createUser,
  //other methods supported, but all are optional
})

##Path Parameters Path parameters are also supported. Example:

//handles cases such as /user/10/info
mux.Handle("/user/:userId/info", userInfo)

the path parameters will be translated into request parameters (available on req.URL.Query() before your handler is called)

##TODO