Software Engineering Fundamentals (SEF): MS.NET Coding Standards

Presentation overview
SOLID principles
KISS, DRY, YAGNI principles
Code readability
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

SOLID principles
Defined by Robert C. Martin (not all elaborated by him)
Acronym by Michael Feathers
Maintainability, extensibility, robustness
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Single Responsibility Principle
SRP: A class should have only one reason to change.
Advantages?
Small and simple to understand classes
Easy to test
Easy to switch implementations
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Open Closed Principle
OCP: A class should be open for extension, but closed for modification.
Advantages?
Minimize risk of introducing bugs into existing functionality
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle
LSP: Let q(x) be a property provable about objects x of type T. Then q(y) should be true for objects y of type S where S is a subtype of T.
LSP: Derived class should not break client code when used in place of base class.
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle
Preconditions cannot be strengthened in a subtype
Postconditions cannot be weakened in a subtype
Invariants of the supertype must be preserved in a subtype
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle
Contravariance of method arguments in the subtype
Covariance of return types in the subtype
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle (contravariance)
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle (covariance)
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle
No new exceptions should be thrown by methods of the subtype
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Liskov Substitution Principle
Advantages?
Imagine big and complex system like Windows OS. You extend a class which is used in tens of other classes. By adhering to LSP risk of breaking whole system is minimized.
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Interface Segregation Principle
ISP: Client should not be forced to depend on methods it does not use.
Advantages?
Implementer is not pushed to implement methods that it doesn’t need
Client has no temptation to use more than it needs
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Dependency Inversion Principle
DIP: High-level modules should not depend on low-level modules. Both should depend on abstractions.
Abstractions should not depend on details. Details should depend on abstractions.
Advantages?
Easy to switch implementations
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Other principles
KISS: Keep It Simple, Stupid
DRY: Don’t Repeat Yourself
YAGNI: You Ain’t Gonna Need It
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Code readability
Clear names
Avoid comments
Formatting
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Tools
StyleCop
JetBrains R#
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Summary
Keep Your POOP SOLID and DRY
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

References
SOLID in C# by Chris Klug (TechEd North America 2014)
Adaptive Code via C#: Agile coding with design patterns and SOLID principles by Gary McLean Hall book
© Accenture. By Maksims Ahadovs & Dmitri Kartashov-Gawski.

Code examples
https://github.com/maksims-ahadovs/SOLID
© Accenture. By Maksims Ahadovs, Dmitri Kartashov-Gawski & Artem Slobolinskyi.