What would you like to see in a generic ToString function?

Question

Lets say you have a generic function called "SafeToString". The purpose is to be able to pass anything in and always get back a sane response without any exceptions. How would you want it to respond to these inputs?

• Null -> Null or String.Empty
• DBNull.Value -> Null, String.Empty, or some text like ""
• Nullable containing a null -> Null, String.Empty, or some text like ""
• FSharpOption containing None -> Null, String.Empty, or "None"
• FSharpOption containing Some(5)-> "5" or "Some(5)"

Answer 1

It is possible to implement such function using extension method. Extension methods work fine with null input parameters.

And yes, I agree that NullReferenceException caused by ToString is very annoying in logging functionality.

Answer 2

I think it's important to be able to distinguish among different sorts of null/empty values. So I'd favor something like:

• null -> "null"
• DBNull.Value -> "DBNull", or maybe "DBNull.Value" if you value the ability to distinguish the value from the name of the class
• Nullable containing null -> "null <typename>". Nullables differ from normal nulls in that they have a type associated with them, and it's potentially useful to know about.
• FSharpOption None -> "None"
• FSharpOption Some(5) -> "Some(5)", just as F# usually does, special thanks to Grauenwolf for checking on this.

Answer 3

This is not answering your question, so forgive me. But you an always use Convert.ToString() on objects to avoid getting exceptions. For instance:

string x = null;
string a = x.ToString(); // throws exception

string b = Convert.ToString(x); // this is fine