Thangavel PrasanthTP

Ruff - Python linter and code formatter

2 min read

Source: https://docs.astral.sh/ruff/ Alternative to linters (like Flake8) and formatters (like Black)

noqa

What does noqa mean?

Resources: https://stackoverflow.com/questions/45346575/what-does-noqa-mean-in-python-comments

Adding # noqa to a line indicates that the linter (a program that automatically checks code quality) should not check this line. Any warnings that code may have generated will be ignored.

That line may have something that “looks bad” to the linter, but the developer understands and intends it to be there for some reason.

  • # noqa has evolved from the # nopep8 syntax used in previous releases of flake8
  • # noqa is supported by IDEs, like PyCharm, for use with their built-in code inspection tools
  • # noqa can be used as a pre-commit directive, such that prior to new commits an inspection process must complete
  • # noqa can be used to ignore all warnings or given specific warnings to ignore. For example, # noqa: F401 will ignore an unused imported module warning.

Example

Resources: https://www.alpharithms.com/noqa-python-501210/ As an example, consider the following code:

import os
print("Hello, world!")

This code imports the os module but doesn’t use it. If one wanted to use the # noqa tool to suppress a PEP8 warning, it could be written as such:

import os  # noqa
print("Hello, world!")

This will ignore all warnings. However, if one were only to want to ignore a specific warning (PEP8 F401 imported but not used), it could be done as such:

import os  # noqa: F401
print("Hello, world!")

# noqa: N815

This is a linting directive that tells the code linter to ignore a specific rule:

  • noqa = “no quality assurance” - tells the linter to skip checking this line
  • N815 is a specific linting rule code

N815 typically refers to a rule about variable naming conventions - it’s probably complaining that variableNameA uses camelCase instead of snake_case (which would be variable_name_a in Python)

The comment is added to Suppress the linter warning about the camelCase naming convention (likely because this field name matches an external API or database schema).

This is a common pattern when working with external APIs or databases that use different naming conventions than your local codebase.

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