flake8-simplify

A flake8 plugin that helps you simplify your code.

Installation

Install with pip:

pip install flake8-simplify

Python 3.6 to 3.8 are supported.

Usage

Just call flake8 . in your package or flake your.py:

$ flake8 .
./foo/__init__.py:690:12: SIM101 Multiple isinstance-calls which can be merged into a single call for variable 'other'

Rules

SIM101: Multiple isinstance-calls which can be merged into a single call by using a tuple as a second argument.
SIM102: Use a single if-statement instead of nested if-statements
SIM103: Return the boolean condition directly
SIM104: Use 'yield from iterable' (introduced in Python 3.3, see PEP 380)
SIM105: Use 'contextlib.suppress(...)' instead of try-except-pass
SIM106: Handle error-cases first
SIM107: Don't use return in try/except and finally.
SIM108: Use the ternary operator if it's reasonable.
SIM201: Use 'a != b' instead of 'not a == b'
SIM202: Use 'a == b' instead of 'not a != b'
SIM203: Use 'a not in b' instead of 'not (a in b)'
SIM204: Use 'a >= b' instead of 'not (a < b)'
SIM205: Use 'a > b' instead of 'not (a <= b)'
SIM206: Use 'a <= b' instead of 'not (a > b)'
SIM207: Use 'a < b' instead of 'not (a <= b)'
SIM208: Use 'a' instead of 'not (not a)'
SIM210: Use 'bool(a)' instead of 'True if a else False'
SIM211: Use 'not a' instead of 'False if a else True'
SIM212: Use 'a if a else b' instead of 'b if not a else a'
SIM220: Use 'False' instead of 'a and not a'
SIM221: Use 'True' instead of 'a or not a'
SIM222: Use 'True' instead of '... or True'
SIM223: Use 'False' instead of '... and False'
SIM300: Use 'age == 42' instead of '42 == age' (Yoda-Conditions)

The SIM201 - SIM208 rules have one good reason to be ignored: When you are checking an error condition:

if not correct_condition:
    handle_error()  # e.g. raise Exception

Examples

SIM101

# Bad
isinstance(a, int) or isinstance(a, float)

# Good
isinstance(a, (int, float))

SIM102

# Bad
if a:
    if b:
        c

# Good
if a and b:
    c

SIM107

# Bad: This example returns 3!
def foo():
    try:
        1 / 0
        return "1"
    except:
        return "2"
    finally:
        return "3"


# Good
def foo():
    return_value = None
    try:
        1 / 0
        return_value = "1"
    except:
        return_value = "2"
    finally:
        return_value = "3"  # you might also want to check if "except" happened
    return return_value

SIM108

# Bad
if a:
    b = c
else:
    b = d

# Good
b = c if a else d

SIM201

# Bad
not a == b

# Good
a != b

SIM202

# Bad
not a != b

# Good
a == b

SIM203

# Bad
not a in b

# Good
a not in b

SIM204

# Bad
not a < b

# Good
a >= b

SIM205

# Bad
not a <= b

# Good
a > b

SIM206

# Bad
not a > b

# Good
a <= b

SIM207

# Bad
not a >= b

# Good
a < b

SIM208

# Bad
not (not a)

# Good
a

SIM210

# Bad
True if a else False

# Good
bool(a)

SIM211

# Bad
False if a else True

# Good
not a

SIM212

# Bad
b if not a else a

# Good
a if a else b

SIM220

# Bad
a and not a

# Good
False

SIM221

# Bad
a or not a

# Good
True

SIM222

# Bad
... or True

# Good
True

SIM223

# Bad
... and False

# Good
False

SIM300

# Bad; This is called a "Yoda-Condition"
42 == age

# Good
age == 42

Skylion007 / flake8-simplify