Top-level code shouldn’t be filled with details about files and stacks and queues and arrays and characters whose parents couldn’t think of better names for them than i, j, and k. Top-level code should describe the problem that’s being solved. It should be packed with descriptive class names and routine calls that indicate exactly what the program is doing, not cluttered with details about opening a file as “read only.”
“If it’s hard to comment, either it’s bad code or you don’t understand it well enough. Either way, you need to spend more time on the code, so the time you spent commenting wasn’t wasted because it pointed you to required work.”
In software development, nontechnical managers are common, as are managers who have technical experience but who are 10 years behind the times. Technically competent, technically current managers are rare. If you work for one, do whatever you can to keep your job. It’s an unusual treat.
Modeling real-world objects might not be the only reason to create a class, but it’s still a good reason! Create a class for each real-world object type that your program models. Put the data needed for the object into the class, and then build service routines that model the behavior of the object.
Anytime you find yourself looking at a class’s implementation to figure out how to use the class, you’re not programming to the interface; you’re programming through the interface to the implementation. If you’re programming through the interface, encapsulation is broken, and once encapsulation starts to break down, abstraction won’t be far behind.
Abstract data types are exciting because you can use them to manipulate real-world entities rather than low-level, implementation entities. Instead of inserting a node into a linked list, you can add a cell to a spreadsheet, a new type of window to a list of window types, or another passenger car to a train simulation. Tap into the power of being able to work in the problem domain rather than at the low-level implementation domain!
After trying a thousand different materials for a light bulb filament with no success, Thomas Edison was reportedly asked if he felt his time had been wasted since he had discovered nothing. “Nonsense,” Edison is supposed to have replied. “I have discovered a thousand things that don’t work.” In many cases, solving the problem with one approach will produce insights that will enable you to solve the problem using another approach that’s even better.
Modularity’s goal is to make each routine or class like a “black box”: You know what goes in, and you know what comes out, but you don’t know what happens inside.
If you refer to an object as a “house” rather than a combination of glass, wood, and nails, you’re making an abstraction. If you refer to a collection of houses as a “town,” you’re making another abstraction.