Introduced LogEventBuilder instead of NLog.Fluent.LogBuilder

[snakefoot]

Introduces LogEventBuilder as replacement for Fluent.LogBuilder. Alternative to #4044 that skips obsolete of ILogger-interfaces

Obsoleted the old fluent LogBuilder and introduced LogEventBuilder that is available without needing to write using NLog.Fluent. The interfaces are very similar, but the start method is a little different:

• LogBuilder: logger.Info().Message("Hello").Write();
• LogEventBuilder: logger.ForInfoEvent().Message("Hello").Write();

I guess one could change LogEventBuilder to be activated from using Info() but it would generate more noise about ambiguous extensions-methods. But actually I like ForInfoEvent() since it signals that one is starting to define a LogEvent.

Also unsure if I like the Write()-method. Think I prefer .Log() but then the transformation would not be that easy:

• LogEventBuilder: logger.ForInfoEvent().Message("Hello").Log();

The major improvement in LogEventBuilder is there is no allocation if the LogLevel is not enabled. And when the LogLevel is enabled, then it no longer allocates an additional LogBuilder-object (Because LogEventBuilder is a struct on the stack). Resolves #532

[snakefoot]

If #3366 becomes true, then it doesn't make sense to introduce a new interface, that will be removed with NLog 6.0

Guess I will just have just to live with the pain, and change the new LogEventBuilder to work with the very ugly ILogger-api.

[sonarqubecloud]

SonarCloud Quality Gate failed.

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

68.7% Coverage
0.0% Duplication

[snakefoot]

Created wiki-page: https://github.com/NLog/NLog/wiki/Fluent-Logger-API