Calling base constructor in c#

Question

If I inherit from a base class and want to pass something from the constructor of the inherited class to the constructor of the base class, how do I do that?

For example,

If I inherit from the Exception class I want to do something like this:

class MyExceptionClass : Exception
{
     public MyExceptionClass(string message, string extraInfo)
     {
         //This is where it's all falling apart
         base(message);
     }
}

Basically what I want is to be able to pass the string message to the base Exception class

Answer 1

Modify your constructor to the following so that it calls the base class constructor properly:

public class MyExceptionClass : Exception
{
    public MyExceptionClass(string message, string extrainfo) : base(message)
    {
        //other stuff here
    }
}

Note that a constructor is not something that you can call anytime within a method. That's the reason you're getting errors in your call in the constructor body.

Answer 2

Its also worth noting you can chain constructors in your current class by substituting "base" for "this".

Answer 3

public class MyExceptionClass : Exception
{
    public MyExceptionClass(string message,
      Exception innerException): base(message, innerException)
    {
        //other stuff here
    }
}

You can pass inner exception to one of the constructors.

Answer 4

Note you can use methods within the call to the base contructor...

    class MyExceptionClass : Exception
    {
         public MyExceptionClass(string message, string extraInfo) : 
         base(ModifyMessage(message, extraInfo))
         {
         }

         private string ModifyMessage(string message, string extraInfo)
         {
             Trace.WriteLine("message was " + message);
             return message.ToLowerInvariant() + Environment.NewLine + extraInfo;
         }
    }