Lazy log formatter

Pre-commit hook to automatically detect and convert f-strings in Python code used in log calls to lazy log calls, following W1203 Pylint rule:

https://pylint.readthedocs.io/en/stable/user_guide/messages/warning/logging-fstring-interpolation.html

Usage

To use with pre-commit, add the following to your .pre-commit-config.yaml:

- repo: https://github.com/dmar1n/lazy-log-formatter
  rev: 0.4.2
  hooks:
    - id: lazy-log-formatter
    args: ['--fix']

Options

• --fix: Automatically fix f-strings used in log calls to lazy log calls.

Examples

If the --fix option is used, the hook will convert f-strings in log calls to lazy log calls, as follows:

# Before
logger.info(f'Hello {name}')

# After
logger.info('Hello %s', name)

# Before
logger.info(f'Hello {name} {surname}')

# After
logger.info('Hello %s %s', name, surname)

Current limitations

• Only works with logging module. Other logging libraries might not work as expected, such as loguru.
• Multi-line f-strings in the editor are not supported yet (they are simply ignored).

For loguru, see Lazy evaluation of expensive functions:

logger.opt(lazy=True).debug("If sink level <= DEBUG: {x}", x=lambda: expensive_function(2**64))