Perform lazy parsing of the call stack information

[Mumeii]

Hi

I've noticed that there is a enableCallStack option in the category configuration part.

Although it's nice to be able to enable / disable such a feature, I think that it should only concerne the recording of the Error object, not its processing

The processing of those Error object should only be performed lazily, because you can't tell ahead of time if those call stack informations will really be used ...

It all depends on :

• the way the patterns of PatternLayout are configured
• the way the user code play with the logEvents log4js give access to

Because of the previous point, it's hard if not impossible for log4js code to guess it while processing the configuration.

So the best solution should be to use a lazy computation technic I guess ?