Gem Logging

##Log Gem's events

Gem uses a logging facade to log various events. You can implement your own appender to intercept and format Gem's messages.

###IAppender The base interface is IAppender which has the following members

    void Info(string message);
    void Info(string message, params object[] args);

    void Debug(string message);
    void Debug(string message, params object[] args);

    void Warn(string message);
    void Warn(string message, params object[] args);

    void Error(string message);
    void Error(string message, params object[] args);

    void Fatal(string message);
    void Fatal(string message, params object[] args); 

Implement your own logging logic and add your IAppender instance to Gem.Auditor.RegisterAppender(IAppender appender) to intercept the logging events.

###ActionAppender

The ActionAppender implements IAppender and takes an Action and a format template as constructor arguments

    new ActionAppender(echo: Console.WriteLine,
                       formatTemplate: "[%Date{0:G}] %Verbosity - %Message");

Format Template options:

   %Verbosity - The event's verbosity
   %Date{pattern} - The DateTime.Now %Date{0} for default
   %Message - The event's message
   %NewLine - Environment.NewLine

You can add your own formatting rules by adding a new FormattingRule(Regex pattern, Func<string, string> replacementRule) to appender.AddFormatingRules(ActionAppender.FormattingRule[] rules)

  new FormattingRule(pattern: new Regex("%Date{.*}",RegexOptions.Compiled),
                     replacementRule: 
                     msg => String.Format(msg.Replace("%Date", ""),
                                          DateTime.Now)   

###ConfigurableAppender

Additionally you can use the ConfigurableAppender to invoke an action prior an event. The configurableAppender has the following options

  Action<TAppender> Info 
  Action<TAppender> Debug 
  Action<TAppender> Warn 
  Action<TAppender> Error 
  Action<TAppender> Fatal 

  ConfigurableAppender
  .Create(new ActionAppender(echo: Console.WriteLine),
          options =>
          {
              options.Info = 
              appender => Console.BackgroundColor = ConsoleColor.Yellow
              options.Error = 
              appender => Console.BackgroundColor = ConsoleColor.Red
          });