Should I catch and wrap general Exception?

Question

Can following code be considered as a good practice? If not, why?

try
{
    // code that can cause various exceptions.         


        

Answer 1

I think that this issue is very speculative, it often depends on specific case, but I did some research and I will share it. First, I want to express my opinion on code from lain Galloway:

try {
  GetDataFromNetwork("htt[://www.foo.com"); // FormatException?

  GetDataFromNetwork(uriArray[0]); // ArrayIndexOutOfBounds?

  GetDataFromNetwork(null); // ArgumentNull?
}
catch(Exception e)
{
  throw new WeClearlyKnowBetterException(
    "Hey, there's something wrong with your network!", e);
}

If GetDataFromNetwork could throw FormatException, than this external calling should has own method, in which will be handled that exception and it should be converted into custom exception like here:

try {
  GetDataFromNetwork();
} catch (FormatException ex) {
  // here you should wrap exception and add custom message, which will specify occuring problem
}

When I´m creating custom exception for specific application, I extend MyGeneralException from Exception and every more specific exception will extend MyGeneralException. So, at the moment you are wrap into custom exception, you should then put in the method throws MyGeneralException.

I´m using rule, which I took over from more experienced developers than I am, that at the first place, when could be thrown some foreign exception, there it should be wrappped into custom, because you don´t want to be dependent on the other module´s exception.

Then If you will use method anywhere, you will put only MyGeneralException into method signature throws and it will bubble up through the layers of application. It should be catched and processed at the highest level, mostly exception message is used to creating response by some handler, or it could be handled manually.

Mainly during designing exception handling there should be considered, if your library will use third party developers, they are not interest in processing many exceptions.