Module Levels

This example demonstrates how to use module-specific log levels to control logging verbosity for different parts of your application. This is incredibly useful for debugging specific components without being overwhelmed by logs from the entire system.

Code Example

const std = @import("std");
const logly = @import("logly");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

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

    const logger = try logly.Logger.init(allocator);
    defer logger.deinit();

    // Set global level to INFO
    var config = logly.Config.default();
    config.level = .info;
    config.show_module = true;
    logger.configure(config);

    // Create scoped loggers for different modules
    const net_logger = logger.scoped("network");
    const db_logger = logger.scoped("database");
    const ui_logger = logger.scoped("ui");

    // Default behavior (INFO and above)
    try logger.info("Application started", @src());
    try net_logger.info("Network initialized", @src()); // Shows [network]
    try net_logger.debug("Network debug message", @src()); // Hidden (global level is INFO)

    // Set specific level for network module (allow DEBUG)
    try logger.setModuleLevel("network", .debug);
    try logger.info("Changed network module level to DEBUG", @src());

    try net_logger.debug("Network debug message (now visible)", @src());
    try db_logger.debug("Database debug message", @src()); // Still hidden

    // Set specific level for UI module (only ERROR)
    try logger.setModuleLevel("ui", .err);
    try logger.info("Changed UI module level to ERROR", @src());

    try ui_logger.warn("UI warning", @src()); // Hidden (using short alias)
    try ui_logger.err("UI error", @src()); // Visible

    // Verify database still follows global
    try db_logger.info("Database info", @src()); // Visible
}

Expected Output

[INFO] Application started
[network] [INFO] Network initialized
[INFO] Changed network module level to DEBUG
[network] [DEBUG] Network debug message (now visible)
[INFO] Changed UI module level to ERROR
[ui] [ERROR] UI error
[database] [INFO] Database info