Version 1.9.0

This release includes 10 new checks, general bug fixes, and some quality-of-life improvements as well!

Add "use starmap" check (FURB140)

Often times you want to iterate over some zip()'d values, unpack them, and pass each of the values to function. The starmap function gives you a faster and more succinct way to do just that.

The following code:

scores = [85, 100, 60]
passing_scores = [60, 80, 70]

def passed_test(score: int, passing_score: int) -> bool:
    return score >= passing_score

passed_all_tests = all(
    passed_test(score, passing_score)
    for score, passing_score
    in zip(scores, passing_scores)
)

Can be re-written as follows:

from itertools import starmap

scores = [85, 100, 60]
passing_scores = [60, 80, 70]

def passed_test(score: int, passing_score: int) -> bool:
    return score >= passing_score

passed_all_tests = all(starmap(passed_test, zip(scores, passing_scores)))

Add "pathlib exists" check (FURB141)

When checking whether a file exists or not, try and use the more modern pathlib module instead of os.path.

This:

import os

if os.path.exists("filename"):
    pass

Can be written like this:

from pathlib import Path

if Path("filename").exists():
    pass

Add "no set op in for loop" check (FURB142)

When you want to add/remove a bunch of items to/from a set, don't use a for loop, call the appropriate method on the set itself.

For example, this code:

sentence = "hello world"
vowels = "aeiou"
letters = set(sentence)

for vowel in vowels:
    letters.discard(vowel)

Can be rewritten like so:

sentence = "hello world"
vowels = "aeiou"
letters = set(sentence)

letters.difference_update(vowels)

# or
letters -= set(vowels)

Add "no or default" check (FURB143)

Don't check an expression to see if it is falsey then assign the same falsey value to it. For example, if an expression used to be of type int | None, checking if the expression is falsey would make sense, since it could be None or 0. But, if the expression is changed to be of type int, the falsey value is just 0, so setting it to 0 if it is falsey (0) is redundant.

This:

def is_markdown_header(line: str) -> bool:
    return (line or "").startswith("#")

Can be written like so:

def is_markdown_header(line: str) -> bool:
    return line.startswith("#")

Add "pathlib unlink" check (FURB144)

When removing a file, use the more modern Path.unlink() method instead of os.remove() or os.unlink(): The pathlib module allows for more flexibility when it comes to traversing folders, building file paths, and accessing/modifying files.

This:

import os

os.remove("filename")

Can be written as:

from pathlib import Path

Path("filename").unlink()

Add "no slice copy" check (FURB145)

Don't use a slice expression (with no bounds) to make a copy of something, use the more readable .copy() method instead.

For example, this:

nums = [3.1415, 1234]
copy = nums[:]

Can be rewritten as:

nums = [3.1415, 1234]
copy = nums.copy()

Add "pathlib is file" check (FURB146)

Don't use the os.path.isfile (or similar) functions, use the more modern pathlib module instead:

if os.path.isfile("file.txt"):
    pass

Can be rewritten as:

if Path("file.txt").is_file():
    pass

Add "pathlib join" check (FURB147)

When joining strings to make a filepath, use the more modern and flexible Path() object instead of os.path.join:

Bad:

with open(os.path.join("folder", "file"), "w") as f:
    f.write("hello world!")

Good:

from pathlib import Path

with open(Path("folder", "file"), "w") as f:
    f.write("hello world!")

# even better ...

with Path("folder", "file").open("w") as f:
    f.write("hello world!")

# even better ...

Path("folder", "file").write_text("hello world!")

Add "no ignored enumerate" check (FURB148)

Don't use enumerate() if you are disregarding either the index or the value:

books = ["Ender's Game", "The Black Swan"]

for index, _ in enumerate(books):
    print(index)

for _, book in enumerate(books):
    print(book)

This instead should be written as:

books = ["Ender's Game", "The Black Swan"]

for index in range(len(books)):
    print(index)

for book in books:
    print(book)

Add "no is bool compare" check (FURB149)

Don't use is or == to check if a boolean is True or False, simply use the name itself:

failed = True

if failed is True:
    print("You failed")

Should be written as:

failed = True

if failed:
    print("You failed")

Allow for comma-separated ignore, enable, and disable CLI flags

Previously, if you wanted to enable/disable/ignore multiple checks at once, you would have to write:

$ refurb src --disable FURB123 --disable FURB124 --disable FURB125

Now you write it like this instead:

$ refurb src --disable FURB123,FURB124,FURB125

What's Changed

• Add "use starmap" check by @dosisod in #137
• Add ability to separate ignore, enable, and disable CLI flags with commas by @dosisod in #138
• Add "pathlib exists" check by @dosisod in #139
• Add "no set in for loop" check by @dosisod in #140
• Fix .pyi files taking precedence over .py files by @dosisod in #141
• Add "no or default" check by @dosisod in #142
• Add "pathlib unlink" check by @dosisod in #143
• Add "no slice copy" check by @dosisod in #145
• Add "is file" pathlib check by @dosisod in #147
• Add noqa comments to test files by @dosisod in #148
• Add "pathlib join" check by @dosisod in #149
• Colorize CI Output by @dosisod in #150
• Fix FURB135 false positives by @dosisod in #153
• Add "no ignored enumerate" check by @dosisod in #154
• Fix typo in no_unecessary_cast explanation by @jaoxford in #156
• Fix FURB145 emitting error for non-slice index expressions by @dosisod in #157
• Bump packages by @dosisod in #158
• Add is operator to FURB124 (use equal chain) by @dosisod in #159
• Add "no is bool compare" check by @dosisod in #160
• Update FURB149 to include == and != by @dosisod in #161

New Contributors

• @jaoxford made their first contribution in #156

Full Changelog: v1.8.0...v1.9.0