AixLog

Header-only C++ logging library

Features

Single header file implementation
- Simply include and use it!
- No dependcies, just vanilla C++11
Permissive MIT license
Use ostream operator <<
- Unobtrusive, typesafe and expressive
- Easy to switch from existing "cout logging"
Fancy name
Native support for various platforms (through Sinks)
- Linux, Unix: Syslog
- macOS: Unified logging (os_log), Syslog (<10.12)
- Android: Android Log
- Windows: Event log, OutputDebugString
Several Sinks:
- cout
- cerr
- Sink with custom callback function
  - implement your own log sink in a lambda with a single line of code
- Easy to add more...
Manipulators for
- Different log levels: TRACE, DEBUG, INFO, NOTICE, WARNING, ERROR, FATAL
  LOG(ERROR) << "some error happened!"
  LOG(DEBUG) << "Just a debug message"
- Conditional logging: simply put COND(bool) in front
  LOG(INFO) << COND(false) << "will not be logged\n"
  LOG(INFO) << COND(true) << "will be logged\n"
- Support for tags:
  LOG(INFO, "my tag") << "some message"
  ...is the same as...
  LOG(INFO) << TAG("my tag") << "some message"
- Capture function and line number and timestamp
- Two different log types "normal" and "special": LOG(INFO) << SPECIAL << "some special message"
  - special might be used for syslog, while normal is used for console output
  - => Only special tagged messages will go to syslog
- Support for colors:
  - Foreground: LOG(INFO) << COLOR(red) << "red foreground"
  - Foreground and background: LOG(INFO) << COLOR(yellow, blue) << "yellow on blue background"

Basic usage

To use AixLog, you must once pass a log sink to AixLog:Log::init, e.g. a SinkCout:

AixLog::Log::init<AixLog::SinkCout>(AixLog::Severity::trace, AixLog::Type::normal);
LOG(INFO) << "Hello, World!\n";

This will print

2017-09-28 11-01-16.049 [Info] (main) Hello, World!

There are two overloads for AixLog:Log::init:

one creates and returns an instance of a Sink (as in the example above)
```
auto sink = AixLog::Log::init<AixLog::SinkCout>(AixLog::Severity::trace, AixLog::Type::normal);
```
The sink can be used to change the severity or to remove it from the Logger

one takes a vector of Sinks

auto sink_cout = make_shared<AixLog::SinkCout>(AixLog::Severity::trace, AixLog::Type::normal);
auto sink_file = make_shared<AixLog::SinkFile>(AixLog::Severity::trace, AixLog::Type::all, "logfile.log");
AixLog::Log::init({sink_cout, sink_file});

This will log to both: cout and to file logfile.log

Advanced usage

You can easily fit AixLog to your needs by adding your own sink, that derives from the Sink class. Or even more simple, by using SinkCallback with a custom call back function:

AixLog::Log::init<AixLog::SinkCallback>(AixLog::Severity::trace, AixLog::Type::all, 
	[](const AixLog::Metadata& metadata, const std::string& message)
	{
		cout << "Callback:\n\tmsg:   " << message << "\n\ttag:   " << metadata.tag.text << "\n\tsever: " << AixLog::Log::to_string(metadata.severity) << " (" << (int)metadata.severity << ")\n\ttype:  " << (metadata.type == AixLog::Type::normal?"normal":"special") << "\n";
		if (metadata.timestamp)
			cout << "\ttime:  " << metadata.timestamp.to_string() << "\n";
		if (metadata.function)
			cout << "\tfunc:  " << metadata.function.name << "\n\tline:  " << metadata.function.line << "\n\tfile:  " << metadata.function.file << "\n";
	}
);
LOG(INFO) << TAG("test") << "Hello, Lambda!\n";