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How to Find the Stinky Parts of Your Code (Part IV)

by Maximiliano ContieriNovember 17th, 2020

Too Long; Didn't Read

Part I can be found here, Part II, Part III is here and Part V Here. This is part IV. How to Find the Stinky Parts of Your Code (Part IV) How to find the stinky parts of your code (Part I) Part I: The road to programming hell is paved with global variables. Part V: The code smells are just hints of something that might be wrong. They are not rigid rules. We see several symptoms and situations that make us doubt the quality of our development.

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Are we done on code smells? Guess not.

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 IV. Part I can be found here, Part II here , Part III is here and Part V Here.

Code Smell 16 - Ripple Effect

Small changes yield unexpected problems.

Photo by Jack Tindall on Unsplash

Problems

Coupling

Coupling: The One and Only Software Designing Problem

Solutions

Decouple.
Cover with tests.
Refactor and isolate what is changing.
Depend on interfaces.

Examples

Legacy Systems

Sample Code

Wrong

Right

Detection

It is not easy to detect problems before they happen. Mutation Testing and root cause analysis of single points of failures may help.

Conclusion

There are multiple strategies to deal with Legacy and coupled systems. We should deal with this problem before it explodes under our eyes.

More info

How to Decouple a Legacy System

Architecture is the tension between coupling and cohesion.

Neal Ford

40+ Thought-Provoking Software Engineering Quotes

Code Smell 17 - Global Functions

Discouraged by Object-Oriented Programmings, Many mixed languages support it. And developers abuse them.

Photo by Mae Mu on Unsplash

Problems

Coupling
Readability
Maintainability
Testability

Solutions

Wrap the function in a context object.

Examples

External Resources Access, Database access, Time and Operating System resources.

Sample Code

Wrong

Right

Detection

Many modern languages avoid them. For the permissive ones, scope rules can be applied and automatically checked.

Conclusion

Structured programming considers global functions harmful. Yet, we can observe some bad practices cross paradigm boundaries.

Relations

Singleton and Classes are global points of access.

More Info

Wikipedia

The road to programming hell is paved with global variables.

Steve McConnell

Code Smell 18 - Static Functions

Yet another global access coupled with laziness.

Photo by Alex Azabache on Unsplash

Problems

Coupling
Testability
Protocol Overloading
Cohesion

Solutions

Class Single Responsibility Principle is to create instance. Honor it.
Delegate method to instance.
Create stateless objects. Don't call them helpers.

Examples

Static class methods
Static attributes

Sample Code

Wrong

Right

Detection

We can enforce a policy to avoid static methods (all class methods but constructors).

Conclusion

Class are globals disguised. Polluting their protocol with "library methods" breaks cohesion and generates coupling. We should extract static with refactorings.

Relations

Singleton Pattern: The Root of All Evil

More info

Single Responsibility Principle

There is no programming problem that can't be solved with one more level of indirection.

John McCarthy

Code Smell 19 - Optional Arguments

Disguised as a friendly shortcut is another coupling smell.

Problems

Coupling
Unexpected results
Side effects
Ripple Effect
In languages with optional arguments but limited to basic types, we need to set a flag and add an accidental IF (another smell).

Solutions

Make arguments explicit.
All function calls must have same arity.
Use Named Parameters if your language supports them.

Sample Code

Wrong

Right

Detection

Detection is easy if language supports optional arguments.

Conclusion

Be explicit. Favor readability over shorter (and more coupled) function call.

More info

The trouble with programmers is that you can never tell what a programmer is doing until it’s too late.

Seymour Cray

Code Smell 20: Premature Optimization

Planning ahead of time needs a crystal ball no developer has.

Photo by Markus Spiske on Unsplash

Problems

Coupling
Testability
Readability
YAGNI

Solutions

Create great models and bijections first.
Create a conclusive benchmark once the model is working.
Design for Performance.
Use Test Driven Development technique. It always favors the simplest solution.

Examples

Weird data structures
Caches
Singletons

Sample Code

Wrong

Right

Detection

This is a design smell so it can not be detected by mechanical tools (yet).

Conclusion

Defer performance decisions until functional models are mature enough.

Donald Knuth created/compiled the best/fastest algorithms and data structures. With great wisdom he warned us of abuse. Why do we think we are smarter than him?

More info

Programmers waste enormous amounts of time worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered.

Donald Knuth