Discussion on: Facades should not have Working Plumbing

[Sean G. Wright]

What are your thoughts on moving the error handling to a decorating class that wraps the facade? Something dedicated to error handling...

The same could be done for logging or caching to keep cross cutting out of the business logic.

[Matt Eland]

Often what I'll do is either use a private method inside the facade for standard error handling / logging if there's a lot of overlap or use a static class in C# with extension method support so, the class might look like this for logging:

public static ErrorExtensions {

  public void LogError(this Exception ex) {
    // Do some actual error logging here
    Console.WriteLine(ex.Message);
  }

}

and then in my handler I might do:

catch (InvalidOperationException ex) { 
  ex.LogError();
}

If, for some reason, you have multiple facades in an application (can happen if you support different types of external callers, for example), you can extract a base class for all facades and add protected methods for these cross-cutting concerns.

The other thing you could consider is following an Action pattern where you have a single method that does standard stuff like validation and error handling and it just takes in a function that it invokes for the implementation-specific logic.