This week Allen is troubled by circles, Michael talks like a game show host, and Joe announces it’s twins as we continue our deep dive into the classic Clean Code book by Robert C. Martin.
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For the full show notes, visit: http://www.codingblocks.net/episode55.
This week’s survey: What type of development floats your boat?
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- Class should begin with a list of variables
- public static constant (or read only)
- private static
- private instance
- public functions
- private utility methods after the public function that calls it
- “Seldom a good reason to have a public variable”
- If a variable needs to be protected in order to be accessed by a test, so be it
Classes should be small
- Rather than count lines, count responsibilities
- Just because it’s small doesn’t mean it’s good – could still have too many responsibilities
- If you cannot derive a good class name, it’s probably too large / too broad a scope
- “Weasel” words like Processor, Manager, Super, usually indicate too many responsibilities
- We should be able to describe a class in 25 words without using the words “if”, “and”, “or”, or “but”.
Classes should adhere to SRP
- SRP, Single Responsibility Principle (Wikipedia): The S in SOLID
- A class or module should have one and only one reason to change
- Identifying responsibilities can help us refactor into better, more concise classes
- SRP is easy to follow but usually the most abused concept
- Most people are focused on getting something done, so organizing the code goes to the wayside
- There is the concern of ballooning the number of files / classes that must be traversed to understand an application
- Would you rather organize drawers by just throwing everything into two drawers, or would you like well separated filing cabinets?
- Many small classes is better
- Large, multipurpose classes force us to scroll through code that we don’t need to know about right now.
- Classes should have a small number of instance variables
- Methods should affect as many variables in the class as possible to achieve “high cohesion”
- When variables aren’t used by many methods, those are probably begging for a new class
- When classes lose cohesion, it’s time to split them up.
- Breaking classes into smaller, simpler functions reduces the event that one function will break another
- Subclassing properly can help reduce number of breaks in existing code
- “Private method behavior that applies only to a small subset of a class can be a useful heuristic for spotting potential areas for improvement.”
- OCP, Open Close Principle (Wikipedia): The O in SOLID
- Classes should be open for extension but closed for modifications
- Ideally, we add new functionality by extending the system, not modifying the existing code.
Isolating from Change
- A client class depending on concrete details is at risk when those details change
- Using a good base / abstract class can make testing easier as you can create repeatable tests
- Making code more testable makes it more reusable in effect
- DIP, Dependency Inversion Principle (Wikipedia): The D in SOLID
- Classes should depend on abstractions, not concrete details
Resources We Like
Of course we’re going to mention Clean Code.
Tip of the Week
- Trade in your old tech books (or other stuff). Check out this link at Amazon for the details.
- GUID Performance in SQL Server as a Primary Key. See this popular answer on StackOverflow.
git archiveto Git the files, not the repository. See the git-archive documentation and this popular answer on StackOverflow.
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Peace, love, and code.