How to Find The Stinky Parts of Your Code (Part X)

More code smells. No joke.We see several symptoms and situations that make us doubt the quality of our development.

Let's look at some possible solutions.

Most of these smells are just hints of something that might be wrong. They are not rigid rules.

This is part V. Part I can be found here, Part II here, Part III is here, Part IV here, part V, VI, VII, VIII and IX.

Let's continue...

Code Smell 46 — Repeated Code

DRY is our mantra. Teachers tell us to remove duplication. We need to go beyond.

Photo by  on 

Problems

• Code Duplication
• Maintainability

Solutions

1. Find repeated patterns (not repeated code).
2. Create an abstraction.
3. Parametrize abstraction calls.
4. Use composition and never inheritance.
5. Unit test new abstraction.

Sample Code

Wrong

Right

Detection

Linters can find repeated code.There are not very good finding similar patterns.Maybe soon machine learning will help us find such abstractions automatically.For now, it is up to us, humans.

Examples

Tags

• Duplication

Conclusion

Repeated code is always a smell.Copying and pasting code is always a shame.With our refactoring tools, we need to accept the duplication remove challenge trusting our tests as a safety net.

More info

Copy and paste is a design error.

David Parnas

Code Smell 47 — Diagrams

Diagrams are not code. They cannot be a code smell. They are just Diagram Smells.

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Problems

• Maintainability
• Trash code
• Code Duplication
• Diagrams focus only on structure (accidental) and not behavior (essential).

Solutions

1. Use diagrams only to communicate ideas with other humans.
2. Program on your favorite IDE.Thrash all diagrams.
3. Even the ones generated from the source code.
4. Trust your tests. They are alive and well maintained.
5. Use  technique.

Sample Code

Wrong

Right

Detection

We can remove all code annotations and forbid them by policy.

Examples

Conclusion

Designing is a contact sport. We need to prototype and learn from our running models.Papers and JPGs don’t run. They live in the utopic world where everything works smoothly. was a very hot trend back in the 90s. No good system was developed with these tools.

More info

• Laziness Chapter II: Code Wizards

The Diagram is Not the Model. The model is not the diagram. It is an abstraction, a set of concepts and relationships between them.

Eric Evans

Code Smell 48 — Code Without Standards

Working on a solo project is easy. Unless you go back to it after some months. Working with many other developers requires some agreements.

Photo by De Jesus de Blas — Russia

Problems

• Maintainability
• Readability

Solutions

1. Automate your styles and indentation.
2. Enforce agreed policies.

Sample Code

Wrong

Correct sample taken from Sandro 

Right

The right example has several other smells, but we keep it loyal to its GIT version in order to show only code standardization issues.

Detection

Linters and IDEs should test coding standards before a merge request is approved.We can add our own  related to Objects, Classes, Interfaces, Modules etc.

Examples

Tags

• Standardization

Conclusion

Use coding standards in your projects.A well-written clean code always follows standards about naming conventions, formatting and code style.Such standards are helpful because they make things clear and deterministic for the ones who read your code, including yourself.Code styling should be automatic and mandatory on large organizations to enforce .

More info

• What Exactly Is A Name: The Quest [Part I]

The nice thing about standards is that there are so many to choose from.

Andrew S. Tannenbaum

Code Smell 49 — Caches

Caches are sexy. They are a one-night stand. We need to avoid them in a long-term relationship.

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Problems

• Coupling
• Testability
• Cache invalidation.
• Maintainability
• Premature Optimization
• Erratic Behavior
• Lack of transparency
• Non-Deterministic behavior

Solutions

1. If you have a conclusive benchmark and are willing to pay for some coupling: Put an object in the middle.
2. Unit test all your invalidation scenarios. Experience shows we face them in an incremental way.
3. Look for a real world cache metaphor and model it.

Sample Code

Wrong

Right

Detection

This is a design smell.It will be difficult to enforce by policy.

Tags

• Premature Optimization

Conclusion

Caches should be functional and intelligent.In this way we can manage invalidation.General purpose caches are suitable only for low level objects like operating systems, files and streams.We shouldn’t cache domain objects.

This page is hosted on a cached website.

More Info

There are only two hard things in Computer Science: cache invalidation and naming things.

Phil Karlton

Code Smell 50 — Object Keys

Primary keys, IDs, references. The first attribute we add to our objects. They don’t exist in the real world.

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Problems

• Coupling
• Accidental Implementation
•  Violation.

Solutions

1. Reference object to objects.
2. Build a .
3. Only use keys if you need to provide an external (accidental) reference. Databases, APIs, Serializations.
4. Use dark keys or  when possible.
5. If you are afraid of getting a big relation graph use proxies or lazy loading.
6. Don’t use DTOs.

Sample Code

Wrong

Right

Detection

This is a design policy.

We can enforce business objects to warn us if we define an attribute or function including the sequence id.

Tags

• Accidental

Conclusion

Ids are not necessary for OOP. You reference objects (essential) and never ids (accidental).In case you need to provide a reference out of your system’s scope (APIs, interfaces, Serializations) use dark and meaningless IDs (GUIDs).

More info

• What is (wrong with) software?
• The One and Only Software Design Principle

The nice thing about standards is that there are so many to choose from.

David Wheeler

We are done for some time. But we are pretty sure we will come across even more smells very soon!I keep getting more suggestions on , so they won't be the last!