What problems can violations of SOLID principles lead to?

Violating SOLID principles can lead to the following problems:

• Fragility: Changes in one part of the system can unintentionally affect other, seemingly unrelated parts.
• Rigidity: The system is difficult to change, as modifications require significant effort and refactoring in many places.
• Immobility: System components are hard to reuse in other projects or even in other parts of the same project.

Specifically, each principle violation is associated with certain problems:

• Single Responsibility Principle (SRP): A class with multiple responsibilities becomes difficult to maintain and modify. Changes related to one responsibility can break functionality related to another.
• Open/Closed Principle (OCP): If classes are not open for extension but closed for modification, adding new functionality requires changing existing code, increasing the risk of errors.
• Liskov Substitution Principle (LSP): Violating this principle leads to subclasses that cannot be used in place of base classes without changing program behavior. This can cause unexpected errors and complicate testing.
• Interface Segregation Principle (ISP): "Fat" interfaces containing too many methods force classes to implement methods they do not need. This complicates class implementation and maintenance.
• Dependency Inversion Principle (DIP): Dependence on concrete implementations rather than abstractions complicates replacing dependent components and testing. High-level modules become tied to low-level details.