Overriding built-in default ignores through an extension

[asottile]

In GitLab by @snoack on Jan 10, 2019, 14:17

We'd like to centralize our flake8 configuration through an extension, rather than duplicating the error codes to be selected/ignored in each of our project's tox.ini. It's already possible to add default ignores and selects through an extension:

    @classmethod
    def add_options(cls, parser):
        parser.extend_default_ignore(['D1'])
        parser.extend_default_select(['E226'])

However, if I select an error code that flake8 ignores by default, the built-in default ignore takes precedence. There is also an remove_default_ignore() method but it only removes ignores that have been preiosly added by this plugin, it doesn't have any effect on the built-in default ignores either.

[asottile]

In GitLab by @snoack on Jan 10, 2019, 15:09

changed title from Overriding built-in default ignores though an extension to Overriding built-in default ignores th{+r+}ough an extension

[asottile]

In GitLab by @snoack on Jan 10, 2019, 15:12

changed the description

[asottile]

In GitLab by @sigmavirus24 on Jan 11, 2019, 04:06

To be brief (because I don't have oodles of time right now to respond, frankly) this isn't what these were designed for. We'd probably want an entirely separate set of APIs for a "plugin" that defines a style guide which we don't have today.

[asottile]

In GitLab by @warsaw on Mar 11, 2019, 15:52

I have a similar use case. I want to add a new code in a new version of my plugin, but I would like to suppress it by default. Only if a user calls flake8 with --select=U999 (let's say 999 is my new code), would you get this error reported. I believe this issue covers the fact that this is not currently possible.

[asottile]

In GitLab by @warsaw on Mar 11, 2019, 15:59

mentioned in merge request warsaw/flufl.flake8!1

[asottile]

In GitLab by @asottile on Mar 11, 2019, 22:30

One way to do that with the current facilities is to separate the "optional" things into a separate "plugin" (can be in the same distribution)

For instance:

[options.entry_points]
flake8.extension =
    U1 = foo.MainPlugin
    U9 = foo.ExperimentalPlugin

And then in your plugin set

class ExperimentalPlugin:
    # ...
    off_by_default = True

Then users can opt into this set of optional codes with

--enable-extension=U9

It ~works (we're using this strategy at work), I think we'd have a better solution with the --extend-select proposed in #365 (similar to already-implemented --extend-ignore)

[sco1]

Question on this via PyCQA/flake8-bugbear#266, am I correct that the following should now yield an ignored-by-default error code (B950 in this case) on the main branch? flake8-bugbear uses extend-default-ignore to add the opinionated codes.

$ pip install flake8-bugbear
$ pip install --force git+https://github.com/pycqa/flake8@main
$ flake8 --version
4.0.1 (flake8-bugbear: 22.6.22, mccabe: 0.7.0, pycodestyle: 2.8.0, pyflakes: 2.4.0) CPython 3.10.2
on Windows
$ echo "foo = 'foo'" > bug.py
$ flake8 --extend-ignore=E501 --extend-select=B950 --max-line-length=9 bug.py

Verbose output:

$ flake8 -vv --extend-ignore=E501 --extend-select=B950 --max-line-length=9 bug.py
flake8                    MainProcess     69 DEBUG    Added a None logging handler to logger root at flake8
flake8.options.manager    MainProcess    117 DEBUG    Registered option "Option(-q, --quiet, action='count', default=0, help='Report only file names, or nothing. This option is repeatable.')".
flake8.options.manager    MainProcess    117 DEBUG    Registered option "Option(--color, default='auto', choices=('auto', 'always', 'never'), help='Whether to use color in output.  Defaults to `%(default)s`.')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--count, action='store_true', help='Print total number of errors to standard output and set the exit code to 1 if total is not empty.')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--diff, action='store_true', help='(DEPRECATED) Report changes only within line number ranges in the unified diff provided on standard in by the user.')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--exclude, default='.svn,CVS,.bzr,.hg,.git,__pycache__,.tox,.nox,.eggs,*.egg', type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=True), help='Comma-separated list of files or directories to exclude. (Default: %(default)s)', metavar='patterns')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--extend-exclude, default='', type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=True), help='Comma-separated list of files or directories to add to the list of excluded ones.', metavar='patterns')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--filename, default='*.py', type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Only check for filenames matching the patterns in this comma-separated list. (Default: %(default)s)', metavar='patterns')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--stdin-display-name, default='stdin', help='The name used when reporting errors from code passed via stdin. This is useful for editors piping the file contents to flake8. (Default: %(default)s)')".
flake8.options.manager    MainProcess    118 DEBUG    Registered option "Option(--format, default='default', help='Format errors according to the chosen formatter.', metavar='format')".
flake8.options.manager    MainProcess    119 DEBUG    Registered option "Option(--hang-closing, action='store_true', help="Hang closing bracket instead of matching indentation of opening bracket's line.")".
flake8.options.manager    MainProcess    119 DEBUG    Registered option "Option(--ignore, type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Comma-separated list of error codes to ignore (or skip). For example, ``--ignore=E4,E51,W234``. (Default: E121,E123,E126,E226,E24,E704,W503,W504)', metavar='errors')".
flake8.options.manager    MainProcess    119 DEBUG    Registered option "Option(--extend-ignore, type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Comma-separated list of error codes to add to the list of ignored ones. For example, ``--extend-ignore=E4,E51,W234``.', metavar='errors')".
flake8.options.manager    MainProcess    119 DEBUG    Registered option "Option(--per-file-ignores, default='', help='A pairing of filenames and violation codes that defines which violations to ignore in a particular file. The filenames can be specified in a manner similar to the ``--exclude`` option and the violations work similarly to the ``--ignore`` and ``--select`` options.')".
flake8.options.manager    MainProcess    119 DEBUG    Registered option "Option(--max-line-length, default=79, type=<class 'int'>, help='Maximum allowed line length for the entirety of this run. (Default: %(default)s)', metavar='n')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--max-doc-length, default=None, type=<class 'int'>, help='Maximum allowed doc line length for the entirety of this run. (Default: %(default)s)', metavar='n')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--indent-size, default=4, type=<class 'int'>, help='Number of spaces used for indentation (Default: %(default)s)', metavar='n')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--select, type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Comma-separated list of error codes to enable. For example, ``--select=E4,E51,W234``. (Default: E,F,W,C90)', metavar='errors')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--extend-select, type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Comma-separated list of error codes to add to the list of selected ones. For example, ``--extend-select=E4,E51,W234``.', metavar='errors')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--disable-noqa, action='store_true', default=False, help='Disable the effect of "# noqa". This will report errors on lines with "# noqa" at the end.')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--show-source, action='store_true', help='Show the source generate each error or warning.')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--no-show-source, action='store_false', dest='show_source', help='Negate --show-source')".
flake8.options.manager    MainProcess    120 DEBUG    Registered option "Option(--statistics, action='store_true', help='Count errors.')".
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--exit-zero, action='store_true', help='Exit with status code "0" even if there are errors.')".
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(-j, --jobs, default='auto', type=<class 'flake8.main.options.JobsArgument'>, help='Number of subprocesses to use to run checks in parallel. This is ignored on Windows. The default, "auto", will auto-detect the number of processors available to use. (Default: %(default)s)')".
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--tee, action='store_true', default=False, help='Write to stdout and output-file.')".
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--benchmark, action='store_true', default=False, help='Print benchmark information about this run of Flake8')".
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--bug-report, action='store_true', help='Print information necessary when preparing a bug report')".
flake8.options.manager    MainProcess    121 DEBUG    Extending default ignore list with ['B901', 'B902', 'B903', 'B904', 'B950']
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--extend-immutable-calls, default=[], type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='Skip B008 test for additional immutable calls.')".
flake8.options.manager    MainProcess    121 DEBUG    Extending default select list with ['B']
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--max-complexity, action='store', default=-1, type=<class 'int'>, help='McCabe complexity threshold')".
flake8.options.manager    MainProcess    121 DEBUG    Extending default select list with ['C90']
flake8.options.manager    MainProcess    121 DEBUG    Registered option "Option(--builtins, type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=False), help='define more built-ins, comma separated')".
flake8.options.manager    MainProcess    122 DEBUG    Registered option "Option(--doctests, action='store_true', default=False, help='also check syntax of the doctests')".
flake8.options.manager    MainProcess    122 DEBUG    Registered option "Option(--include-in-doctest, default='', type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=True), dest='include_in_doctest', help='Run doctests only on these files')".
flake8.options.manager    MainProcess    122 DEBUG    Registered option "Option(--exclude-from-doctest, default='', type=functools.partial(<function _flake8_normalize at 0x000001D2BA61F520>, comma_separated_list=True, normalize_paths=True), dest='exclude_from_doctest', help='Skip these files when running doctests')".
flake8.options.manager    MainProcess    122 DEBUG    Extending default select list with ['F']
flake8.options.manager    MainProcess    122 DEBUG    Extending default select list with ['E']
flake8.options.manager    MainProcess    122 DEBUG    Extending default select list with ['W']
flake8.checker            MainProcess    122 WARNING  The multiprocessing module is not available. Ignoring --jobs arguments.
flake8.checker            MainProcess    123 INFO     Making checkers
flake8.discover_files     MainProcess    123 DEBUG    "C:\Users\sco1\Documents\Github\testcode\bug.py" has not been excluded
flake8.checker            MainProcess    123 INFO     Checking 1 files
flake8.checker            MainProcess    126 DEBUG    Logical line: "foo = 'xxx'"
flake8.main.application   MainProcess    126 INFO     Finished running
flake8.main.application   MainProcess    127 INFO     Reporting errors
flake8.style_guide        MainProcess    127 DEBUG    The user configured 'E501' to be <Selected.Explicitly: 'explicitly selected'>, <Ignored.Explicitly: 'explicitly ignored'>
flake8.style_guide        MainProcess    127 DEBUG    "E501" will be "Decision.Ignored"
flake8.violation          MainProcess    127 DEBUG    Violation(code='E501', filename='bug.py', line_number=1, column_number=10, text='line too long (11 > 9 characters)', physical_line="foo = 'foo'\n") is not inline ignored
flake8.style_guide        MainProcess    127 DEBUG    The user configured 'B950' to be <Selected.Explicitly: 'explicitly selected'>, <Ignored.Explicitly: 'explicitly ignored'>
flake8.style_guide        MainProcess    127 DEBUG    "B950" will be "Decision.Ignored"
flake8.violation          MainProcess    127 DEBUG    Violation(code='B950', filename='bug.py', line_number=1, column_number=12, text='line too long (11 > 9 characters)', physical_line="foo = 'foo'\n") is not inline ignored
flake8.main.application   MainProcess    127 INFO     Found a total of 2 violations and reported 0

[asottile]

it's a little weird, but by using --extend-ignore that ~slightly opts out of the "am I using the default ignore list" -- I wonder if there should be a middle ground to accommodate for that?

[sco1]

Ah I see, if --extend-ignore is omitted then we go from:

flake8.style_guide        MainProcess    127 DEBUG    The user configured 'B950' to be <Selected.Explicitly: 'explicitly selected'>, <Ignored.Explicitly: 'explicitly ignored'>

to:

flake8.style_guide        MainProcess    127 DEBUG    The user configured 'B950' to be <Selected.Explicitly: 'explicitly selected'>, <Ignored.Implicitly: 'implicitly ignored'>

For both paths I think I would be expecting that B950 is implicitly ignored, is such a middle ground feasible?

[asottile]

yeah there's probably a better middle ground than assuming any time --extend-ignore happens that the default values are intended to be ignored. let me see if I can make that work ~slightly better

[asottile]

@sco1 should work now after #1609 -- try it out and let me know!

[sco1]

lgtm, thanks for the help :)