DCI - Data, Context and Interaction - Successor to MVC?

Question

What is the best description of Data, Context and Interaction (DCI) to pitch it to an organization?

It's created by Trygve Reenskaug, the creator of the MVC-pattern.

Is it really the successor to MVC or just another pattern? And what are its pros and cons?

Answer 1

Trygve makes a presentation of DCI in https://vimeo.com/8235394

DCI has been created to solve a problem in object orientation: it's too difficult to review OO code.

The code for one use-case in OO is typicall spread out between lots of classes. To understand how the code works, you must also know the relationships between objects in runtime. These relationships aren't set in code, they depend on the situation.

What DCI proposes is that code for a given use-case is separated out from the classes and put into a different artifact called context. Objects of different classes can enter into a relationship in this context and take part in interaction where they have different roles.

The whole point of DCI is to make OO code more readable!

That's how I would pitch it.

Answer 2

The impression I got is that it's not a successor to MVC so much as a complement, for example figure 5 in the artima article on DCI has both. I think it's supposed to help make the distinction between model and controller more sane, or maybe between different part of the controller or different parts of the model.

The basic idea seems to be to split logic for particular actions our of your data classes and move it to traits/mixins/whatever, one per (user) action. You'll have many small pieces of code, instead of a few large pieces. Also, it sounds like adding new mixins is supposed to be "better" than adding functionality to your base classes. The code for individual actions will probably (I think?) be more spread out, but code for different actions should be more clearly and obviously separated.