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Category Archives: Object-Oriented Analysis and Design
Revisiting Nouns and Verbs
There Is No Spoon
Something learned early when studying OOP is to name classes as nouns or noun-phrases and name methods as verbs. It seems like too simple an idea to make better object-oriented designs, but it makes a big difference. In fact, there is reasonable evidence that adherence to this idea could make a design, and ignorance of it could break one. The evidence comes from my own experiences refactoring code as well as what I’ve recently learned while studying Smalltalk.
Naming has such an effect because better names reduce the context an object has, i.e., what an object is aware of versus what it needs awareness of to do its job. Removing unnecessary information raises the level of abstraction providing more opportunity for reuse and minimizes the chance that the message needs changing when requirements change.
A message name constrains the possible interpretations to some extent, which is good. This indicates what the program is doing when the object sends the message and hints to implementing objects the context in which they are operating. However, we should only constrain the meaning of a message as much as necessary and not so much to exclude other valid uses.
To summarize what I’ll be talking about: If an object sends a message that mentions any noun other than those that indicate the parameters it’s passing then there is likely added context and a case for renaming.
Notice I said “likely”. There’s no need to deal in absolutes (as only the Sith do). As I’ve learned more about programming, and life, I’ve learned that nothing is absolute. Everything is relative. You can find exceptions to every rule. Black and white are just acute versions gray.
Messages should only include nouns within their context because messages are ignorant of the things that respond to them and the inner parts of the things that respond to them.
If you remember the movie “The Matrix”*, there is the famous scene when Neo visits The Oracle and meets a boy who bends spoons with his mind. When Neo attempts this, the boy gives him a helpful tip:
Do not try and bend the spoon, that’s impossible. Instead, only try to realize the truth…there is no spoon. Then you will see it is not the spoon that bends, it is only yourself. -Spoon Boy, The Matrix movie
Draft: Putting the Kibosh on Getters and Setters
Perspective
I recently picked up a new book on object-oriented programming called “Object-Oriented Design Heuristics” by Arthur J. Riel. In the book, Riel explains programming’s natural evolution from procedures and data structures to object-oriented. He talks about how programmers adapted their development style to reduce the effects of changes to data structures.
In procedural programming, programmers develop software by decomposing a system into procedures (or functions) that act on a set of shared data structures. One of the problems associated with this type of programming is what Riel calls the “unidirectional relationship between data and behavior”. This unidirectional relationship means you can tell which data a procedure depends on by looking at the procedure (its parameters, local variables, and global variable access), but you can’t tell which procedures use a data structure by looking at the data structure. Take the following pseudocode for example:
Shower Idea: Keyboards and Object-Oriented Design
You know that hypnotic thinking that happens in the shower? I do that outside of the shower. I’m not just staring at the wall. That’s the story of why I’m calling this a shower idea (even though I didn’t think of this in the shower).
I’ll probably post more of these shower ideas in the future. I usually forget to write them down, but I’m going to stop doing that. These ideas aren’t groundbreaking. They’re just interesting food for thought.
Dazed and Confuzzled
Alright, Alright, Alright
For a long time I’ve been on a mission to find the lost parts of object-oriented programming. There is clear evidence that somewhere between its inception and modern programming OOP has lost its definition. Dr. David West says in his book, Object Thinking, “An argument can be made that the contemporary mainstream understanding of objects is but a pale shadow of the original idea. Further, it can be argued that the mainstream understanding of objects is, in practice, antithetical to the original intent.”[1] There is an original form of OOP that promises many benefits, with the foremost benefits being system composability and flexibility. The form of OOP that many use today, and the form being taught today is a diluted version. We typically defer to a structured style that places control procedures in direct command of other procedures and use objects as data structures.
Reoriented
“Education is what remains after one has forgotten what one has learned in school.”
-Albert Einstein
What have I learned about programming, and OOP in general?
One of the biggest eye-openers is very simple. An idea that can easily get lost when using high level languages or discussing the philosophy of what’s right and wrong in programming. It’s also lost on anyone who doesn’t study computer science in school and only programming (/raisehand). Just like we don’t consciously think about tying our shoes, we don’t always think about the intricate roots of programming when we’re doing it.
The idea is that math is the basis for programming, and follows much of the same rules of mathematics. Math and programming both share certain protocols for operating on data sets. Those protocols include things like inputs, outputs, domains, ranges, abstractions, and functions. I’m no math whiz, but I’ll do my best to explain what I mean. Continue reading
Looking in the Mirror
What’s Going on Here?
Object-oriented programming concepts are almost universally problematic for new programmers (including myself). It’s easy enough to find information about these concepts, but my understanding of them always feels incomplete. If you search the Internet you’ll find lots of guidelines to correctly structure and write object-oriented code. There are also various concepts that are important to understand like abstraction, and encapsulation, etc. You’ve probably heard them all by now. If you haven’t heard of these concepts, then get a book on object-oriented programming. My goal is not to explain what’s already been explained elsewhere in great detail. My goal is to try to offer my perspectives on what I learn in order to help programmers on the same path avoid long periods of confusion and frustration. One of the things I hope to do here is analyze my own projects and show why I make specific design choices, what concepts and guidelines do I consider when making my choices, and what my alternative choices are and why I didn’t choose them. Continue reading
