Bulldozer00's Blog

Since my previous post, I’ve been thinking in more detail about how we manage to move an integrated set of static structures and dynamic behaviors out of our heads and into a tree of associated source code files. A friend of mine, Bill Livingston, coined this creative process as “bridging the gap” across the “Gulf Of Human Intellect” (GOHI).

The figure below shows two methods of transcending the GOHI: direct mind-to-code (M2C), and indirect mind-to-model-to-source (M2M2C). The difference is that M2M2C is scale-able where as M2C is not. Note that both methods are iterative adventures.

Past a certain system size (7 +/- 2 interconnected chunks?), no one can naturally fit a big system model entirely within their head without experiencing mental duress. By employing a concrete model as a “cache” between the mind and the code, M2M2C can give large performance and confidence boosts to the mind. But, one has to want to actively learn how to model ideas in order to achieve these benefits.

From Mind-To-Code (M2C)

How do we grow from a freshly minted programmer into a well-rounded, experienced, software engineer? Do we start learning from the top-down about abstract systems, architecture, design, and/or software development processes? Or do we start learning from the bottom up about concrete languages, compilers, linkers, build systems, version control systems?

It’s natural to start from the bottom-up; learning how to program “hands on“. Thus, after learning our first language-specific constructs, we write our first “Hello World” program. We use M2C to dump our mind’s abstract content directly into a concrete main.cpp  file via an automatic, effortless, Vulcan mind-meld process.

Next, we learn, apply, and remember over time a growing set of language and library features, idioms, semantics, and syntax. With the addition of these language technical details into to our mind space, we gain confidence and we can tackle bigger programming problems. We can now hold a fairly detailed vision of bigger programs in our minds – all at once.

From Mind-To-Model-To-Code (M2M2C)

However, as we continue to grow, we start to yearn of building even bigger, more useful, valuable systems that we know we can’t hold together in our minds – all at once. We turn “upward“, stretching our intellectual capabilities toward the abstract stuff in the clouds. We learn how to apply heuristics and patterns to create and capture design and architecture artifacts.

Thus, unless we want to go down the language lawyer/teacher route, we learn how to think outside of the low level “language space“. We start thinking in terms of “design space“, creating cohesive functional units of structure/behavior and the mechanisms of loosely connecting them together for inter-program and intra-program communication.

We learn how to capture these designs via a modeling tool(s) so we can use the concrete design artifacts as a memory aid and personal navigational map to code up, integrate, and test the program(s). The design artifacts also serve double duty as communication aid for others. Since our fragile minds are unreliable, and they don’t scale linearly, the larger the system (in terms of number of units, types of units, size of units, and number of unit-to-unit interfaces), the more imperative it is to capture these artifacts and keep them somewhat in synch with the fleeting images we are continuously munching on in our mind.

We don’t want to record too much detail in our model because the overhead burden would be too great if we had to update the concrete model artifacts every time we changed a previous decision. On the other hand, we don’t want to be too miserly. If we don’t record “just enough” detail, we won’t be able mentally trace back from the artifacts to the “why?” design decisions we made in our head. That’s the “I don’t know why that’s in the code base or how we got here” syndrome.

A Useful Design Tool

For a modeling tool, we can use plain ole paper sketches that use undecipherable “my own personal notation“, or we can use something more rigorous like basic UML diagrams.

For example, take the static structural model of a simple 3 class design in this UML class diagram:

I reverse-engineered this model out of a small section of the code base in an open source software project. If you know UML, you know that the diagram reads as:

• A CBlock “is a” CBlockHeader.
• A CBlock “has” one or more CTransactionRef objects that it creates, owns, and manages during runtime
• A CBlockHeader “has” several data members that it creates, owns, and manages during runtime.

Using this graphic artifact, we can get to a well structured skeleton code base better than trying to hold the entire design in our head at once and then doing that Vulcan mind meld thingy directly to code again.

Using the UML class diagram, I coded up the skeletal structure of the program as three pairs of .h + .cpp files. Some UML tools can auto-generate the code skeletons at the push of a button after the model(s) have been manually entered into the tool’s database. But that would be a huge overkill here.

As a sanity-test, I wrote a main.cpp file that simply creates and destroys an object of each type:

From Mind-To-Model-To-Code: Repeat And Rise

For really big systems, the ephemeral, qualitative, “ilities” and “itys” tend to ominously pop up out of the shadows during the tail end of a lengthy development effort (during the dreaded system integration & testing phases). They suddenly, but understandably, become as important to success as the visible, “functional feature set“.  After all, if your system is dirt slow (low respons-ivity), and/or crashes often (low reliab-ility ), and/or only accommodates half the number of users as desired (low scala-bility), no one may buy it.

So, in summary, we start out as a junior programmer with limited skills:

Then, assuming we don’t stop learning because “we either know it all already or we’ll figure it out on the fly” we start transforming into a more skilled software engineer.