Hi Norbert

2016-04-27 10:43 GMT+02:00 Norbert Hartl <norbert@hartl.name>:

So assuming the Log class would not contain log levels but SysLog would do you could easily override #logClass in your domain object and use it this way

MyDomainClass class>>#logClass
^ SysLog

myDomainObject asLog
warning;
emit

This way we do not need to pollute Object with a lot of methods that are tight to one use case. The call to #warning could be something else that only depends on the Log class you want to use.��

There is one problem with this approach when we split preparation and emitting of log object. It will always produce garbage. If no logs will have interest in myDomainObject or #warning-level messages application will continue create log entries.

I think it is important to minimize cost of logging when nobody have interest on particular event. If debug-level log is disabled then no garbage should be created. If stack traces log is disabled then no stack information should be retrieved anywhere.

To achieve this we should create log entry instances only when we will find any logs for them. It imposes restriction on possible API. At point when we are ready to log something we should have all information which can be part of filter. So if we want to filter logs by domain objects and log-levels we need both parameters in one message send. Then we can ask every registered log for interest about both of them. And only when we will find any one we will create log entry instance for them.