Ignoring Errors with Flake8¶

By default, Flake8 has a list of error codes that it ignores. The list used by a version of Flake8 may be different than the list used by a different version. To see the default list, flake8 --help will show the output with the current default list.

Changing the Ignore List¶

If we want to change the list of ignored codes for a single run, we can use flake8 --ignore to specify a comma-separated list of codes for a specific run on the command-line, e.g.,

flake8 --ignore=E1,E23,W503 path/to/files/ path/to/more/files/

This tells Flake8 to ignore any error codes starting with E1, E23, or W503 while it is running.

Note

The documentation for flake8 --ignore shows examples for how to change the ignore list in the configuration file. See also Configuring Flake8 as well for details about how to use configuration files.

In-line Ignoring Errors¶

In some cases, we might not want to ignore an error code (or class of error codes) for the entirety of our project. Instead, we might want to ignore the specific error code on a specific line. Let’s take for example a line like

example = lambda: 'example'

Sometimes we genuinely need something this simple. We could instead define a function like we normally would. Note, in some contexts this distracts from what is actually happening. In those cases, we can also do:

example = lambda: 'example'  # noqa: E731

This will only ignore the error from pycodestyle that checks for lambda assignments and generates an E731. If there are other errors on the line then those will be reported.

Note

If we ever want to disable Flake8 respecting # noqa comments, we can can refer to flake8 --disable-noqa.

If we instead had more than one error that we wished to ignore, we could list all of the errors with commas separating them:

# noqa: E731,E123

Finally, if we have a particularly bad line of code, we can ignore every error using simply # noqa with nothing after it.

Ignoring Entire Files¶

Imagine a situation where we are adding Flake8 to a codebase. Let’s further imagine that with the exception of a few particularly bad files, we can add Flake8 easily and move on with our lives. There are two ways to ignore the file:

By explicitly adding it to our list of excluded paths (see: flake8 --exclude)
By adding # flake8: noqa to the file

The former is the recommended way of ignoring entire files. By using our exclude list, we can include it in our configuration file and have one central place to find what files aren’t included in Flake8 checks. The latter has the benefit that when we run Flake8 with flake8 --disable-noqa all of the errors in that file will show up without having to modify our configuration. Both exist so we can choose which is better for us.