Testing, Debugging and Refactoring - logging example

[Jakub]

Hello,

could you please exaplain once again what's the difference between non-lambda code and it's lambda version? (Chapter 7: Testing, Debugging and Refactoring, site 98)

non-lambda code:

Logger logger = new Logger();
if (logger.isDebugEnabled()) {
 logger.debug("Look at this: " + expensiveOperation());
}

lambda code:

Logger logger = new Logger();
logger.debug(() -> "Look at this: " + expensiveOperation());

What do we win by using the lambda version? We can hide the isDebugEnabled check in non-lambda code as well - don't we?

[Richard Warburton]

Hi Jakub,

Yeah, we hide the isDebugEnabled() and keep the responsibility of dealing with logging levels encapsulated in the logger. We also don't have the cost of running expensiveOperation() if we aren't in the debug logging level.

[Jakub]

Ahh sure, it's lazy evaluated. Totally missed that. Seems like it takes some time to get the spirit. Thx.