如何通过不同的功能发送文本？

Question

I want to create ac# library with a log function like this:

class MyLogClass
{
    public void log(string format, params object[] args)
    {

        string message = string.Format(format, args);

        // custom function
        log_to_file(message); // or log_to_db() or log_to_txtBox()

    }
}

The idea is to change the function as required, using log_to_file(), log_to_db() or log_to_txtBox().

I was thinking of using a third parameter (before of format) as a delegate to represent a custom function, but I don't know how to do it.

Answer 1

Using a delegate, you'd write something like:

class MyLogClass
{
    public static void Log(Action<string> outputAction, string format,
                           params object[] args)
    {
        string message = string.Format(format, args);
        outputAction(message);
    }
}

Note that the parameter can't come after the args parameter, as the latter is a parameter array (as signified by the params keyword) - and a parameter array can only appear as the final parameter in a declaration.

Alternatively, you could set an action when you create an instance of the class:

class MyLogClass
{
    private readonly Action<string> outputAction;

    public MyLogClass(Action<string> outputAction)
    {
        this.outputAction = outputAction;
    }

    public void Log(string format, params object[] args)
    {
        string message = string.Format(format, args);
        outputAction(message);
    }
}