README

Logging Example

The logger is not part of the framework core. It lives in the example application as an external-style dependency registered by the application bootstrap.

Units:

Mir-Logger/Logger.Port.pas
Mir-Logger/Logger.Options.pas
Mir-Logger/Logger.pas

Port

ILogger = interface
  procedure Log(const Level: TLogLevel; const Message: string);
  procedure Debug(const Message: string);
  procedure Info(const Message: string);
  procedure Warning(const Message: string);
  procedure Error(const Message: string);
end;

Log levels

Logger.Port.pas defines:

TLogLevel = (llDebug, llInfo, llWarning, llError);

Logger.Options.pas maps string values from configuration to this enum.

Valid configured values:

• Debug
• Info
• Warning
• Error

Values are normalized using trim and uppercase comparison.

Options

TLoggerOptions is an example options section:

type
  TLoggerOptions = class(TOptionsSection)
  private
    FLogLevel: string;
    FFilePath: string;

    function GetSectionName: string; override;
  public
    property LogLevel: string read FLogLevel write FLogLevel;
    property FilePath: string read FFilePath write FFilePath;
  end;

The section name is defined by GetSectionName:

function TLoggerOptions.GetSectionName: string;
begin
  Result := 'Logger';
end;

The root app config must contain:

{
  "Logger": {
    "LogLevel": "Info",
    "FilePath": "./Logs/App.log"
  }
}

Registration

The framework does not register the logger by default. The example application registers TLogger and its options in dpr or bootstrap unit:

App.AddOptions<TLoggerOptions>;
App.AddSingleton<ILogger, TLogger>;

TLogger receives its configuration through constructor injection:

constructor TLogger.Create(const AOptions: IOptions<TLoggerOptions>);

Behavior

TLogger writes to:

• console, with ANSI colors by level;
• file, using the configured FilePath.

It validates:

• LogLevel is present;
• FilePath is present;
• the log file path is valid;
• the log file can be opened.

Writes are synchronized using TCriticalSection.