Don't call it "MVP"

Lately there’s been a lot of discussion about an alternative architectural pattern for Android development. The acronym that’s being used to denote this alternative pattern is ”MVP.” I think that “MVP” is an inaccurate and confusing designation for this pattern. In this post, I will say why I think “MVP” is a bad name for the pattern, and I’ll suggest a different name for referring to it.

What is ”MVP?”

There are plenty of blog posts out there that describe the “MVP” pattern, so I’m not going to do that here. If you’re not familiar with MVP, then I suggest checking out Square’s tirade against fragments or Hannes Dorfmann’s post about his library that’s supposed to help with implementing MVP.

Why “MVP” is an Unhelpful Name

The problem with the name ”MVP” is that the Views in the MVP triad are actually quite different from the Views in Android SDK. They each have fundamentally different responsibilities, so we need a way to mark the difference between Android Views and MVP Views. Without clearly marking the difference between them, we make it more difficult to understand the “MVP” pattern and we run the risk of conflating the two object’s responsibilities when we start trying to follow the MVP pattern.

Let me try to clearly distinguish an Android View from an MVP View.

Traditionally, an Android View is generic; it is not application specific. There is no RedditPostTitleView in the Android SDK. Instead, we just have something generic like a TextView. There is no onRedditPostTitleClicked(), but there is a generic onClick() method.

An MVP View, on the other hand, is application specific. The MVP View responds to application-specific messages from the Presenter. It responds to messages like showRedditPosts(). An MVP View also sends application-specific event messages to its Presenter, messages like onRedditPostTitleClicked().

So, Android Views and MVP Views are fundamentally different, but both are present in any Android application that follows the “MVP” pattern. The name “MVP” obscures the difference between these two Views. That’s why I think its unhelpful.

An Alternative Name

Here’s the new name I think we should use instead of “MVP”: MVVTP

The “VT” in the above acronym stands for “ViewTranslator.”

To see why this acronym is more accurate than “MVP,” let’s look a little closer at the responsibilities of Android Views and MVP Views. Remember that Android Views are generic. They’re generic because they need to be reusable. A RedditPostTitleView can only be used in a Reddit client app, so instead we have a generic TextView.

An MVP View, on the other hand, has a different responsibility. It lets the Presenter manipulate what gets drawn on the screen on a more abstract, application-specific level. In other words, an MVP View translates a higher level, application-specific request from the Presenter into code that Android Views can “understand.”

For example, there is no showRedditPosts() method on a RecyclerView, but an MVP View takes a showRedditPosts() message and “says” to an Android View, “Hey. What the Presenter really wants when he says ‘showRedditPosts()’ is ‘recyclerView.setAdapter(redditPostsAdapter)’.

That’s why I think we should call MVP Views “ViewTranslators.” That name more accurately captures their responsibility.

If we recall that MVP Views also forward UI events to their Presenter, we can see another reason why “ViewTranslator” is a better name for an MVP View. When an MVP View forwards a UI event to its Presenter, it is also translating that generic event into an application-specific one. It converts a generic onClick() event from a TextView to an application-specific onRedditTitleClicked() event.

Conclusion

“MVP” is a bad name for the new architectural pattern that Android devs are talking about because it obscures the difference between MVP Views and Android Views. “MVVTP,” where VT stands for “ViewTranslator” is a better name for this pattern because it explicitly marks a difference between Android Views and ViewTranslators. Android Views know how to draw stuff, and they don’t need any application-specific knowledge to do that. ViewTranslators translate application-specific requests from the Presenter into generic messages that Android Views can understand and they translate generic UI events from Views to application-specific events that the Presentercan act on.