Add ILogger methods to write templated messages

[lodejard]

  _logger.WriteTemplate(
    TraceType.Information, 
    "writing {filename} took {milliseconds}ms", 
    theFileName, theTimeElapsed); 

Assuming this would take level, messageTemplate, and params object[] values... Assuming there would be other overloads like InformationTemplate and ErrorTemplate that would call the base one with the enum value. I guess there would be overloads that take an exception also...

The extension method would call the ILogger _logger.Write() with the arguments for object state, Exception eception, Func<object, Exception, string> formatter

The state in this case would implement ILoggerStructure, and ILoggerStructure.GetValues() would enumerate the key-value pairs based on {markers} in the template and values in object[].

The formatter in this case would be a callback that downcasts the state object. Assuming the state object is holding onto the information needed to stringify.

[tugberkugurlu]

I cannot resist the temptation as logging is one of my favorite ❤️ topics. So, I will ask 😄

String Interpolation is currently a planned feature for C# 6.0. I wonder how this would look like with string interpolation. I assume it won't effect this as far I can see as the interpolated string seems to be translated to String.Format but I wanted to ask anyway.

[davidfowl]

This is done.