Log Apex Right using Dependency Inversion Principle

The Dependency Inversion Principle says:

Depend in the direction of abstraction. High level modules should not depend upon low level details.

An example of a higher level module depending on lower level details is this logger

public class RulesEngine {
    public RulesEngine(){}
    public void processRule(string rule){
        Log_Message__e logMessage = new Log_Message__e();
        logMessage.Message__c = 'Processing rule: ' + rule;
        EventBus.publish(logMessage);
    }
}

It shouldn’t care how the log is logged, so we want to refactor by extracting the function for logging, so the higher functionality doesn’t need the details.

public class Logger {
    public Logger(){}
    
    public void log(string message){
        Log_Message__e logMessage = new Log_Message__e();
        logMessage.Message__c = message;
        EventBus.publish(logMessage);
    }
}

Now the higher level module can let the lower deal with the details and just care about the abstraction of logging.

public class RulesEngine {
    Logger lgr;
    public RulesEngine(){
        lgr = new Logger();
    }
    
    public void processRule(string rule){
        lgr.log('Processing rule: ' + rule);
    }
}