In a previous article, I had to shorten a bunch of lines that had a row and column value used as indexes to the board array. This repeated pattern is a call-to-action.
We want to encapsulate the logic for referring to a particular place on the board, and for advancing through the board. This is the responsibility of the Iterator pattern.
Spoiler Alert: we don’t get all the way there in this article.
Continue readingThis refactoring is my bread and butter. Functions tend to grow. Eventually, you need to split them. Find a section of the method that has its own self-containerd reason- for existence, and make that its own function.
I have in the back of my head that I want to extract a class that abstracts the boards from this code. I’ve been resisting the urge thus far, as keeping the board as a 2D array of cells is really conducive to sharing with other implementations of this code. However, the following refactoring should work to support either direction: pull out the code that constructs a board from the string. This has the added benefit of making it possible to write a unit test that calls tree_to_solution_string without having to parse all of the strings.
Continue readingAs the refactoring process continues, we will continue to decompose the large central class and functions. Right now, the SudokuSolver class is performing two functions. It is holding and managing the list of the puzzles, and it is solving them.
The heart of this code is the function tree_to_solution_string. Right now, I can’t call that by itself, as the SudokuSolver creates a bunch of helper objects before running through the whole set of tests. how can we tease this apart?
Continue readingWhile writing the last article, I noticed that I had made a bunch of little changes to the files without explicitly meaning to. I didn’t include them in the diffs. However, on my screen, I have a bunch of changes that appear to be…not changes:
Continue readingThe typical approach to Data handling is
We want out code to reflect that structure. In doing so, we make it much easier to adapt the code to read from different sources and write to different destinations.
Continue readingThe heart of the code is the call to solve a single puzzle; the function tree_to_solution_string. We want to write a test that runs just this function. Getting there is not so easy.
This method is buried deep within the class SudokuSolver. But creating one of these essentially runs the entire code. In fact, we can redo our original test to run the code as a python call as opposed to a subprocess call. Lets’ start with that.
Continue readingOur test takes 5 seconds to run. That is not horrible, but it does not bode well for when we write more tests. We don’t want to explode that number, and we want to be able to write more focused test. I’m going to do some project setup that will enable us to do more development, including fine grained unit tests.
I’m going to start by using tox.
Continue reading180 lines of code is not horrible, but it is a lot to wrap your mind around all at once. In order to get oriented to the code, we’re going to take on one of the simpler refactorings. We are going to replace a bunch of the magic numbers with symbolic constants.
Continue readingThe code runs. How do me make sure that continues to be the case? Write a test.
Continue readingCongratulations, you got your code to run! You are done! Ship it!. Just don’t expect to be able to read it next month. You need to maintain it. You need to add new features. It is a mess.
Give yourself a well deserved break. Then come back to it.
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