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[Code refactoring] Error Codes

One of my colleges found the following code:
public class BaseFooException : System.Exception
  public int ErrorCode { get; set; }
  public string ResourceMessageKey
      return string.Format("error_{0}", ErrorCode);

public class CustomFooException : BaseFooException
  public CustomFooException()
    ErrorCode = 5;
The error code was introduce to manage the resources of UI. For each specific error code we had an “error_[code]” in the resources file. When we look over this for the first time we could say that it is okay and the implementation looks good.
But, if we look more dipper we can observe that we introduce information related to UI in the all the core components. When an exception from a core component is throw, the component don’t needs to know at that level that some resources are mapped to that error.
In this happy case, each exception type has a different exception code. We cannot have two exception references from the same custom exception and have two different error codes. Because of this, we can map the error messages for exception using based on the type of the exception.
  • Remove the ErrorCode property and ResourceMessageKey from the base exception class
  • At the UI level, create a resolver, which will resolve the message for each exception from resources file
  • Create/Rename resources items that represent the error message something similar with this “error_[ExceptionType]"
  • Create a Resolver that get the type of exception and extract the string message for the given exception

public class BaseFooClientException : System.Exception

public class CustomFooException : BaseFooException

What other solutions do you have/imagine?


  1. Do you need the Base exception then? You can just let the resolver resolve all kinds of exceptions.


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