A type that can measure and format the current time.
This trait is used by
Format to include a timestamp with each
Event when it is logged.
Notable default implementations of this trait are
(). The former prints the
current time as reported by
std::time::SystemTime, and the latter does not print the current
time at all.
FormatTime is also automatically implemented for any function pointer with the
The full list of provided implementations can be found in
Measure and write out the current time.
format_time is called, implementors should get the current time using their desired
mechanism, and write it out to the given
fmt::Write. Implementors must insert a trailing
space themselves if they wish to separate the time from subsequent log message text.