logger

C++ log abstraction

Inspiration

The Dr.Dobb's Journal (no longer in print) had published some articles that used the C++ left-shift operator (operator()<<) to define a logger based on std::ostream<>.

• DDJ October 2007 article by Petru Marginean, September 05, 2007: "Logging in C++"
• DDJ ???? article by Filip Janiszewski, January 31, 2013: "A Lightweight Logger for C++"

Unfortunately, neither article or code is available from the website anymore. But the basic premise was to take advantage of a destructer called when the temporary instance representing a logger "line" goes out-of-scope.

These articles had been written without C++11, and I've used this theme multiple times since, to use more recent language features. However, one of the more obnoxious issues was the persistent need for C macros, to report the line number and file name from the source code (via __LINE__ and __FILE__).

Fortunately, C++20 has the new source_location. feature 😃

Goals

• Implement logger from scratch in C++20, without macros, to support std::ostream<>.
• Thread safe
• Exception safe
• Portable
• Efficient (limited overhead when optimized)
• Const-correct semantics
• Fully unit-tested
• Use stack where possible.
• Characterize use of heap.
• Investigate limited support for async-signal safe usage.