Log Levels

Logly-Zig supports 10 built-in log levels, each with a specific priority, color, and use case.

Level Overview

Level	Priority	Color	ANSI	Method	Alias	Use Case
TRACE	5	Cyan	36	logger.trace()	-	Very detailed debugging
DEBUG	10	Blue	34	logger.debug()	-	Debugging information
INFO	20	White	37	logger.info()	-	General information
NOTICE	22	Bright Cyan	96	logger.notice()	-	Important notices
SUCCESS	25	Green	32	logger.success()	-	Successful operations
WARNING	30	Yellow	33	logger.warning()	warn()	Warning messages
ERROR	40	Red	31	logger.err()	-	Error conditions
FAIL	45	Magenta	35	logger.fail()	-	Operation failures
CRITICAL	50	Bright Red	91	logger.critical()	crit()	Critical system errors
FATAL	55	White on Red	97;41	logger.fatal()	-	Fatal system errors

Whole-Line Coloring

Logly colors the entire log line (timestamp, level tag, and message), not just the level name:

[2024-01-15 10:30:45] [WARNING] Low disk space    <- Entire line is yellow
[2024-01-15 10:30:46] [ERROR] Connection failed   <- Entire line is red
[2024-01-15 10:30:47] [FATAL] System crash        <- Entire line is white on red background

Usage

// Enable colors on Windows first
_ = logly.Terminal.enableAnsiColors();

// All methods accept optional @src() for clickable file:line output
try logger.trace("Detailed trace information", @src());   // Cyan line
try logger.debug("Debug information", @src());            // Blue line
try logger.info("Application started", @src());           // White line
try logger.notice("Important notice", @src());            // Bright cyan line
try logger.success("Operation completed!", @src());       // Green line
try logger.warning("Warning message", @src());            // Yellow line
try logger.warn("Short alias for warning", @src());       // Yellow line (alias)
try logger.err("Error occurred", @src());                 // Red line
try logger.fail("Operation failed", @src());              // Magenta line
try logger.critical("Critical system error!", @src());    // Bright red line
try logger.crit("Short alias for critical", @src());      // Bright red line (alias)
try logger.fatal("Fatal system error!", @src());          // White on red background

Note: Each level also has a formatted variant (e.g., tracef, infof, noticef, fatalf) that accepts a format string and arguments. See Formatting for details.

Custom Levels

Create your own log levels with custom priorities and colors:

// Add custom levels
try logger.addCustomLevel("AUDIT", 35, "35");      // Magenta (between WARNING and ERR)
try logger.addCustomLevel("SECURITY", 48, "91;1"); // Bold bright red (between FAIL and CRITICAL)

// Use custom levels
try logger.custom("AUDIT", "Security event detected", @src());
try logger.customf("SECURITY", "Unauthorized access from {s}", .{"192.168.1.1"}, @src());

Level Filtering

You can configure the minimum log level to output. Messages below this level will be ignored.

var config = logly.Config.default();
config.level = .info; // Ignore TRACE and DEBUG
logger.configure(config);

Priority Order

The levels follow this priority order (lowest to highest):

TRACE (5) < DEBUG (10) < INFO (20) < NOTICE (22) < SUCCESS (25) < WARNING (30) < ERROR (40) < FAIL (45) < CRITICAL (50) < FATAL (55)

When you set a minimum level, only messages at that level or higher will be logged.

Module Levels

You can set different log levels for specific modules. This allows you to enable debug logging for a specific part of your application while keeping the rest at a higher level.

// Set global level to INFO
config.level = .info;
logger.configure(config);

// Enable DEBUG for network module
try logger.setModuleLevel("network", .debug);

// Create a scoped logger
const net_logger = logger.scoped("network");
try net_logger.debug("This will be logged", @src());

To use module-specific logging, use the scoped() method to create a logger instance for that module.