I just came across the C# 5 Caller Info Attributes (http://msdn.microsoft.com/en-us/library/hh534540.aspx).
This seems like a very useful feature, and I've read up some documentation (http://www.codeproject.com/Tips/606379/Caller-Info-Attributes-in-Csharp).
However, I'm just wondering: Why does one have to pass in default values? How are they used?
The following example code shows how one would use the Caller Info Attributes:
public static void ShowCallerInfo([CallerMemberName]
string callerName = null, [CallerFilePath] string
callerFilePath = null, [CallerLineNumber] int callerLine=-1)
{
Console.WriteLine("Caller Name: {0}", callerName);
Console.WriteLine("Caller FilePath: {0}", callerFilePath);
Console.WriteLine("Caller Line number: {0}", callerLine);
}
My question is: What are the default values of null, null, and -1 used for? How is the code above different from:
public static void ShowCallerInfo([CallerMemberName]
string callerName = "hello", [CallerFilePath] string
callerFilePath = "world", [CallerLineNumber] int callerLine=-42)
{
Console.WriteLine("Caller Name: {0}", callerName);
Console.WriteLine("Caller FilePath: {0}", callerFilePath);
Console.WriteLine("Caller Line number: {0}", callerLine);
}
The way I understand it, these are optional parameters, and the compiler supplies the default value, replacing whatever default value we assign. In that case, why are we specifying the default values? Is there some weird edge case where the compiler may not be able to fill in the values, and resorts to the defaults we had supplied? If not, then why are we being asked to enter this data? It seems rather clumsy to ask devs to supply defaults which won't ever be used.
Disclaimer: I tried googling this but I wasn't able to find anything. I'm almost afraid of asking questions on SO because most such newbie questions are met with such hostility, but as a last resort I'm going to hazard a question. Moderators/senior users, no offense intended - I really did try and find information elsewhere before posting this.