What the heck is SOLID?

SOLID is presented as a set of five design principles for software development that help keep object-oriented code structured, readable, and maintainable. The post says these ideas make future changes easier, especially as a project grows or becomes harder to revisit.

It then explains each principle with examples: Single Responsibility says each method or function should have one goal; Open-Closed says code should be extendable without rewriting existing classes; Liskov Substitution says a base class should be replaceable by its subclass; Interface Segregation says interfaces should be split so classes only implement what they need; Dependency Inversion says high-level modules should depend on abstractions rather than concrete details.

Reading notes

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• SOLID is an acronym for five design principles in software development.
• The goal is to keep code structured, readable, and maintainable.
• The Single Responsibility Principle says each method or function should have only one goal or reason for change.
• The Open-Closed Principle says software entities should be open for extension but closed for modification.
• The Liskov Substitution Principle says a base class should be interchangeable with a subclass without breaking the program.
• The Interface Segregation Principle says interfaces should be separated so classes do not have to implement methods they do not need.
• The Dependency Inversion Principle says high-level modules should depend on abstractions, not on concrete low-level modules.
• The post uses C# examples to show how each principle changes class design.