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Untangling Nested Code

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There is code out there that is ugly. I mean really ugly. I know, can you believe it? But it's true. One such example of really ugly code is code that has lots of deeply nested calls. The tests are trying to test a dozen different methods in every case. The methods look so simple with just a few lines and a few calls. And then those methods called have a few lines and a few calls. And then again, a dozen or more different calls deep.

We want to use private helper methods to make our code clearer and cleaner. Calling methods is also largely what programming is about. But sometimes we overdo it. Deep call hierarchies are difficult to follow and they can mask what the code is really doing. Each call means that we have to look all over a class to see what actually happens. This makes debugging hard. This makes testing even harder.

Say we have the following code:

class DataLoader { void loadNationalData(Nation nation, int year, DataReader reader) { for (State state : natio…

Break Down Code to Make It DRYer

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We are always looking to make our code DRYer. Code that is not repeated is easier to maintain. We can make a change in just one place rather than hunting for different incarnations in many different places. Making code DRYer is not always easy, and sometimes how to remove the duplication is not apparent.

Let's say we have the following two functions:

public List<Stats> processLines(File file) { List<Stats> stats = new ArrayList<>(); for (String line : lines(file)) { Data data = extractDataFrom(line); Stats dataStats = calculateStatsFor(data); stats.add(dataStats); } return stats; } public List<Stats> processLines(List<File> files) { List<Stats> stats = new ArrayList<>(); int fileNumber = 0; for (File file : files) { for (String line : lines(file)) { Data data = extractDataFrom(line, fileNumber); Stats dataStats = calculateStatsFor(data); st…