Added support for passing a function/closure to the logger #424
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…ge instead of a raw string. This allows log messages to be lazily evaluated only when actually emitted (which can yield substantial performance benefits). This was already possible using logging level-based conditional logging, but the syntax was much messier:
if (logger.level.level < 5000) logger.trace(JSON.stringify(myBigObject));
vs
logger.trace(() => JSON.stringify(myBigObject));
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I can see this being useful, so thanks for the PR. My only concern is that there could be someone out there that's logging a function somehow, and this would now execute that function. Would you be able to add a config parameter to turn this feature on and off - with "off" being the default. A boolean at the top level of config would be fine. |
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Leaving this open because it's still a good idea, but it'll need to some work to port to tap tests and allow for turning it off and on. |
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IMO this is a great feature and its more natural. I would recommend a major version bump upon inclusion of this, and allow the config default to be true, noting that in a v2->v3 upgrade guide Or include this in current version with default off, but make sure to make default on in eventual log4js@3.0.0 |
Added support for passing a function/closure to the logger as a message instead of a raw string. This allows log messages to be lazily evaluated only when actually emitted (which can yield substantial performance benefits). This was already possible using logging level-based conditional logging, but the syntax was much messier:
vs
logger.trace(() => JSON.stringify(myBigObject));