atugushev / flake8-printf-formatting Goto Github PK

(Partially copied from MichaelKim0407/flake8-use-fstring#22, as this plugin also suffers from the same issue.)

The following code triggers a MOD001 error:

a = 42
b"y=%d" % a

However, using an f-string with a byte string is a syntax error:

>>> bf"y={a}"
  File "<stdin>", line 1
    bf"y={a}"
      ^^^^^^^
SyntaxError: invalid syntax

And .format() is not an option either:

>>> b"y={}".format(a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'bytes' object has no attribute 'format'

The only other option is .join() or string concatenation, which are less elegant IMO.

(I could also do "y={}".format(a).encode("utf-8"), but that doesn't always work right if there are byte literals in the string.)

Generally I prefer using f-strings or .format(), but when the string contains { and/or } I find it cleaner to just use %-formatting instead:

"bar_format": "{l_bar}{bar:%d}{r_bar}" % (columns - 42),

The alternatives are much harder to read:

"bar_format": f"{{l_bar}}{{bar:{columns - 42}}}{{r_bar}}"

"bar_format": "{{l_bar}}{{bar:{:d}}}{{r_bar}}".format(columns - 42)

It would be nice to have an option to automatically allow %-formatting in such cases without having to add # noqa.

Classes Num, Str, Bytes, NameConstant, and Ellipsis are considered deprecated in favor of ast.Constant since python 3.8.

Consider something like:

isinstance(node.left.value, (bytes, str))

See: https://bugs.python.org/issue32892

In Python 3.8, the importlib_metadata package was implemented in the standard library as importlib.metadata (Python docs)

You may want to add this snippet to flake8_printf_formatting.py and update the install requires in setup.cfg

try:
    import importlib.metadata as importlib_metadata
except ImportError:
    import importlib_metadata  # python_version<'3.8'

I can also submit a PR if that would be of interest

For searchability, this is the error from flake8: flake8.exceptions.FailedToLoadPlugin: Flake8 failed to load plugin "MOD" due to No module named 'importlib_metadata'.