LogLayer

One Way Log Level Manager ​

NPM Version

Log Level Manager Source

A log level manager that keeps log levels synchronized between parent and children. Parent changes affect children, but child changes do not affect parents. Changes only apply to a parent and their children (not separate instances).

Installation ​

bash
npm install @loglayer/log-level-manager-one-way
bash
yarn add @loglayer/log-level-manager-one-way
bash
pnpm add @loglayer/log-level-manager-one-way

Usage ​

typescript
import { LogLayer, ConsoleTransport, LogLevel } from "loglayer";
import { OneWayLogLevelManager } from '@loglayer/log-level-manager-one-way';

const parentLog = new LogLayer({
  transport: new ConsoleTransport({
    logger: console
  }),
}).withLogLevelManager(new OneWayLogLevelManager());

const childLog = parentLog.child();

// Parent changes affect children
parentLog.setLevel(LogLevel.warn);

parentLog.info('This will not be logged'); // Not logged
childLog.info('This will not be logged'); // Not logged (affected by parent)

// Child changes do not affect parent
childLog.setLevel(LogLevel.debug);

parentLog.debug('This will not be logged'); // Not logged (parent still at warn)
childLog.debug('This will be logged'); // Logged (child changed to debug)

Nested Children ​

typescript
import { LogLayer, ConsoleTransport, LogLevel } from "loglayer";
import { OneWayLogLevelManager } from '@loglayer/log-level-manager-one-way';

const parentLog = new LogLayer({
  transport: new ConsoleTransport({
    logger: console
  }),
}).withLogLevelManager(new OneWayLogLevelManager());

const childLog = parentLog.child();
const grandchildLog = childLog.child();

// Parent changes affect all descendants
parentLog.setLevel(LogLevel.error);

parentLog.warn('This will not be logged'); // Not logged
childLog.warn('This will not be logged'); // Not logged (affected by parent)
grandchildLog.warn('This will not be logged'); // Not logged (affected by parent)

// Child changes only affect that child and its descendants
childLog.setLevel(LogLevel.debug);

parentLog.warn('This will not be logged'); // Not logged (parent still at error)
childLog.debug('This will be logged'); // Logged (child changed to debug)
grandchildLog.debug('This will be logged'); // Logged (affected by child)

Behavior ​

  • One-way Propagation: Parent changes propagate to all children, but child changes do not affect parents
  • Hierarchical: Changes apply only within a parent-child hierarchy, not across separate logger instances
  • Independent Child Containers: Each child has its own log level container, initialized from the parent but independent after creation

Use Cases ​

  • Module-level Log Level Control: When you want to control log levels for a specific module and all its sub-modules
  • Hierarchical Logging: When you need different log levels for different parts of your application hierarchy