Custom formatting

spdlog's default logging format is of the form:

[2014-31-10 23:46:59.678] [info] [mylogger] Some message

There are 2 ways to customize log format:

• Use logger.set_pattern(std::string pattern_string) (recommended)

• Implement custom formatter that implements the formatter interface and call set_formatter(std::share_ptr<custom_formatter>)

Customizing log format using set_pattern:

Can be set globally to all loggers:

spdlog::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***");

or to a specific logger object:

some_logger.set_pattern(">>>>>>>>> %H:%M:%S %z %v <<<<<<<<<");

Format strings & efficiency

Whenever the user calls set_pattern("..") the library "compiles" the new pattern to an internal efficient representation.

This way the performance stays very good even with complex patterns (no parsing of the pattern on each log write)

Pattern flags:

Pattern flags are in the form of %[flag] and resembles [strftime] (http://www.cplusplus.com/reference/ctime/strftime/) function.. Anything that is not pattern flag will be logged as is..

|flag|meaning|example| |-------|:-------:|:-----:|------:| |%v|The actual text to log|"some user text"| |%t|thread id|"1232"| |%n|logger's name|"some logger name" |%l|The log level of the message|"debug", "info", etc| |%a|Abbreviated weekday name|"Thu"| |%A|Full weekday name|"Thursday"| |%b|Abbreviated month name|"Aug"| |%B|Full month name|"August"| |%c|Date and time representation|"Thu Aug 23 15:35:46 2014"| |%C|Year in 2 digits|"14"| |%Y|Year in 4 digits|"2014"| |%D or %x|Short MM/DD/YY date|"08/23/01"| |%m|Month 1-12|"11"| |%d|Day of month 1-31|"29"| |%H|Hours in 24 format 0-23|"23"| |%I|Hours in 12 format 1-12|"11"| |%M|Minutes 0-59|"59"| |%S|Minutes 0-59|"58"| |%e|Millisecond part of the current second 0-999|"678"| |%p|AM/PM|"AM"| |%r|12 hour clock|"02:55:02 pm"| |%R|24-hour HH:MM time, equivalent to %H:%M|"23:55"| |%T or %X|ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S|"23:55:59"| |%z|ISO 8601 offset from UTC in timezone ([+/-]HH:MM)|"+02:00"| |%%|The % sign|"%"| |%+|spdlog's default format|"[2014-31-10 23:46:59.678] [info] [mylogger] Some message"