tstring-logger

Python logging with template strings with support for conditional (lazy) execution of functions in log messages.

Provides TStringLogger(logging.Logger) and sets it as the default logger class upon import tstring_logger

A Template String may embed function calls with a !fn format specifier. They will only be executed if the logger is active.

Example

import logging
import tstring_logger

def expensive_function(x):
    time.sleep(1)
    return 2 * x

logging.basicConfig()
lg = logging.getLogger("demo")
hour = datetime.datetime.now().hour
print(1)
lg.debug(test := t"The thing happened with {expensive_function:!fn} {7} at hour {hour}.")
print(2)
lg.setLevel(logging.DEBUG)
lg.debug(test)
print(3)

will quickly print 1 and 2, then pause a second before 3 appears after DEBUG:demo:The thing happened with 14 at hour 16. Since expensive_function takes a single argument, the 7 is passed to the function while hour renders in the usual way.

The logger uses the embed function of tstring-util.