RxJava extension: favor Observable.defer + ReplaySubject over Observable.create

Hi @kittinunf 😃

Creating an Observable using its static built-in create method could lead to unexpected results, and because of that its usage is generally disallowed.

This method requires advanced knowledge about building operators and data sources; please consider other standard methods first

Extracted from the official docs.

That’s why I would recommend to change the current implementation to use defer and ReplaySubject:

private fun <T : Any> Request.rx_response(deserializable: Deserializable<T>): Observable<Pair<Response, T>> =
        Observable.defer {
            val source = ReplaySubject.create<Pair<Response, T>>()
            response(deserializable) { request, response, result ->
                when (result) {
                    is Result.Success -> {
                        source.onNext(response to result.value)
                        source.onCompleted()
                    }

                    is Result.Failure -> {
                        source.onError(result.error)
                    }
                }
            }
            source.doOnSubscribe { this.cancel() }
        }

If you agree with this proposal I could make a PR 😃

[kittinunf]

This should be closed then! Thanks @VictorAlbertos so much for helping me out ❤️

[VictorAlbertos]

Of course 😃 Already done at #138