Business Logic Validation and the Decorator Design Pattern
Often, developers have a need to implement complex and changing business logic in our applications. One way to handle agile business validation is with the Decorator design pattern.
While implementing the pattern might seem like more work upfront versus inline logic, the benefits to any application with shifting business needs can be considerable.
In the link provided below, the Decorator design pattern is utilized to provide various bank account scenarios. While the implementation provided is not perfect, it at least fleshes out how this pattern can be useful for business logic validation.
Read the blog post, by Eric De Carufel:
Using Decorator (or Wrapper) Design Patterns to Add Validation to an Object