When chaining a base constructor, how can I reuse initialization code in an overload

.net, c#

Solution

Factor it out into a separate method, and call that method from both constructors.

public class CustomException : Exception
{
    private readonly string _customField;

    public CustomException(string customField, string message)
        : base(message)
    {
        Init(out _customField, customField);
    }

    public CustomException(string customField)
        : base()
    {
        Init(out _customField, customField);
    }

    private Init(out string _customField, string customField)
    {
        _customField = customField;
    }
}

Problem

Please see question embedded in comment below. ``` public class CustomException : Exception { private readonly string _customField; public CustomException(string customField, string message) : base(message) { // What's the best way to reuse the customField initialization code in the // overloaded constructor? Something like this(customField) } public CustomException(string customField) { _customField = customField; } } ``` I'm open to considering alternative implementations that reuse the base constructor and minimize initialization code. I'd like to keep the _customField readonly, which is not possible if I extract a separate initialization method.

Original source