Example of SRP in php, use Laravel as example. Jus a brief case about what we usually do while developing project.

1. Deddy Setyadi
SINGLE RESPONSIBILITY PRINCIPLE

2. Single Responsibility Principle
Open-closed
Liskov substitution
Interface segregation
Dependency inversion
S.O.L.I.D

3. Individuals and interactions over processes and tools.
Working software over comprehensive
documentation.
Customer collaboration over contract negotiation.
Responding to change over following a plan.
Agile Development

4. Is Your Code S.T.U.P.I.D?

5. S.T.U.P.I.D Code
Singleton
Tight-Coupling
Untestable
Premature Optimization
Indescriptive Naming
Duplication reference

6. Singleton
It introduces global state, so any code can change its value.
Programs that rely on global state hide their dependencies.
Hard to test.

9. Tight-Coupling
Tightly coupled modules are difficult to reuse & hard to test.
more

10. Untestable
Testing should not be hard!
Most of the time, untestable is caused by tight coupling.

11. Premature Optimization
"Premature optimization is the root of all evil. There is only
cost, and no benefit” - Donald Knuth.
You will just end up with unreadable code.

12. Indescriptive Naming
Name your classes, methods, attributes, and variables properly.
Follow PSR !
You write code for people, not for computers.

13. Duplication
Don’t Repeat Yourself (DRY).
Keep It Simple, Stupid (KISS).
Be lazy the right way - write code only once!

16. Don't feel bad.
Be awesome by writing SOLID code instead!

17. A class should have one, and only one,
reason to change.
Single Responsibility Principle

18. Just because you can add everything you want into your
class doesn't mean that you should.
Ask yourself whether the logic you are introducing should
live in this class or not. Using layers in your application helps a
lot. Split big classes in smaller ones, and avoid god classes.
Single Responsibility Principle

19. But, where do we start?

20. #1 Care
Maybe the things that don’t matter...matter most
Single Responsibility Principle

23. #2 Simplicity
Not focus on solution first, but how it feels to use
Single Responsibility Principle

25. #3 Distrust
Take it in, consider it, but don't necessarily
immediately adopt it
Single Responsibility Principle

26. Demo

27. Writing Software is Hard
- Jeffrey Way -

28. References
https://laracasts.com/lessons/jeffrey-way-laracon-2015-presentation
https://laracasts.com/series/solid-principles-in-php/episodes/1
http://williamdurand.fr/2013/07/30/from-stupid-to-solid-code
http://www.objectmentor.com/resources/articles/srp.pdf
http://stackoverflow.com/questions/8776788/best-practice-on-php-singleton-classes