The most used and (in)famous design pattern in the world is causing us great harm.

Problems

Coupling
Testability
Accidental implementation problems.
Multi threading issues.
Static methods polluting.
Object creation contract violation.
Bijection mismatch.
Memory issues.
Premature Optimization.

Code Smell 20 - Premature Optimization

Maxi Contieri ・ Nov 8 '20

#oop #developing #coding #codesmell

Solutions

Avoid it.
Use contextual unique objects.
Benchmark object creation.

Examples

Database Access
Globals
Loggers
Helpers

Code Smell 22 - Helpers

Maxi Contieri ・ Nov 12 '20

#oop #helpers #codenewbie #beginners

Sample Code

Wrong

God is the archetypical singleton example.

Right

Detection

This is a design pattern. We should avoid it by policy.

We can add linter rules for patterns like 'getInstance()' so new developers cannot infect code with this anti-pattern.

Conclusion

This is an historical mistake already acknowledged by the community. Nevertheless, lazy developers bring it again and again. We need to reach a consensus on its drawbacks.

Relations

Code Smell 06 - Too Clever Programmer

Maxi Contieri ・ Oct 25 '20

#codenewbie #tutorial #beginners

Code Smell 25 - Pattern Abusers

Maxi Contieri ・ Nov 15 '20

#oop #tutorial #programming #patterns

Code Smell 18 — Static Functions

Maxi Contieri ・ Nov 6 '20

#codenewbie #tutorial #development #coding

More info

Singleton: The Root of all Evil

Maxi Contieri ・ Nov 17 '20

#oop #tutorial #codenewbie #programming

Credits

Photo by Maria Teneva on Unsplash

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 32 - Singletons