Logging in Flexx

Flexx uses the standard Python logging facilities, but adds functionality, most notably the ability to filter messages by a string or regexp.

flexx.set_log_level(level, match=None)

Set the logging level and match filter

  • level (str, int) – The verbosity of messages to print. If a str, it can be either DEBUG, INFO, WARNING, ERROR, or CRITICAL. Note that these are for convenience and are equivalent to passing in logging.DEBUG, etc.
  • match (str, regexp, None) – String to match. Only those messages that contain match as a substring (and has the appropriate level) will be displayed. Match can also be a compiled regexp.


If level is DEBUG, the method emitting the log message will be prepended to each log message. Note that if level is DEBUG or if the match option is used, a small overhead is added to each logged message.

class flexx.util.logging.capture_log(level, match=None)

Context manager to capture log messages. Useful for testing. Usage:

with capture_log(level, match) as log:
# log is a list strings (as they would have appeared in the console)