Unit 10
Linters For Code Quality
Task
Copy the following Python code into a file named code_with_lint.py:
import io
from math import *
from time import time
some_global_var = 'GLOBAL VAR NAMES SHOULD BE IN ALL_CAPS_WITH_UNDERSCOES'
def multiply(x, y):
"""
This returns the result of a multiplation of the inputs
"""
some_global_var = 'this is actually a local variable...'
result = x* y
return result
if result == 777:
print("jackpot!")
def is_sum_lucky(x, y):
"""This returns a string describing whether or not the sum of input is lucky
This function first makes sure the inputs are valid and then calculates the
sum. Then, it will determine a message to return based on whether or not
that sum should be considered "lucky"
"""
if x != None:
if y is not None:
result = x+y;
if result == 7:
return 'a lucky number!'
else:
return( 'an unlucky number!')
return ('just a normal number')
class SomeClass:
def __init__(self, some_arg, some_other_arg, verbose = False):
self.some_other_arg = some_other_arg
self.some_arg = some_arg
list_comprehension = [((100/value)*pi) for value in some_arg if value != 0]
time = time()
from datetime import datetime
date_and_time = datetime.now()
return
Code source: https://realpython.com/python-code-quality/
Now run the code against a variety of linters to test the code quality:
- pylint code_with_lint.py
- pyflakes code_with_lint.py
- pycodestyle code_with_lint.py
- pydocstyle code_with_lint.py
Compare the effectiveness of each tool in defining and identifying code quality. What can you conclude about the effectiveness of each approach?
Linters’ output
pylint output
************* Module code_with_lint
code_with_lint.py:27:0: W0301: Unnecessary semicolon (unnecessary-semicolon)
code_with_lint.py:31:0: C0325: Unnecessary parens after 'return' keyword (superfluous-parens)
code_with_lint.py:33:0: C0325: Unnecessary parens after 'return' keyword (superfluous-parens)
code_with_lint.py:44:0: C0304: Final newline missing (missing-final-newline)
code_with_lint.py:1:0: C0114: Missing module docstring (missing-module-docstring)
code_with_lint.py:2:0: W0622: Redefining built-in 'pow' (redefined-builtin)
code_with_lint.py:2:0: W0401: Wildcard import math (wildcard-import)
code_with_lint.py:13:4: W0621: Redefining name 'some_global_var' from outer scope (line 7) (redefined-outer-name)
code_with_lint.py:16:4: W0101: Unreachable code (unreachable)
code_with_lint.py:13:4: W0612: Unused variable 'some_global_var' (unused-variable)
code_with_lint.py:25:7: C0121: Comparison 'x != None' should be 'x is not None' (singleton-comparison)
code_with_lint.py:28:12: R1705: Unnecessary "else" after "return", remove the "else" and de-indent the code inside it (no-else-return)
code_with_lint.py:19:0: R1710: Either all return statements in a function should return an expression, or none of them should. (inconsistent-return-statements)
code_with_lint.py:35:0: C0115: Missing class docstring (missing-class-docstring)
code_with_lint.py:41:8: W0621: Redefining name 'time' from outer scope (line 5) (redefined-outer-name)
code_with_lint.py:41:15: E0601: Using variable 'time' before assignment (used-before-assignment)
code_with_lint.py:42:8: C0415: Import outside toplevel (datetime.datetime) (import-outside-toplevel)
code_with_lint.py:37:4: R1711: Useless return at end of function or method (useless-return)
code_with_lint.py:37:50: W0613: Unused argument 'verbose' (unused-argument)
code_with_lint.py:40:8: W0612: Unused variable 'list_comprehension' (unused-variable)
code_with_lint.py:43:8: W0612: Unused variable 'date_and_time' (unused-variable)
code_with_lint.py:35:0: R0903: Too few public methods (0/2) (too-few-public-methods)
code_with_lint.py:1:0: W0611: Unused import io (unused-import)
code_with_lint.py:5:0: W0611: Unused time imported from time (unused-import)
code_with_lint.py:2:0: W0614: Unused import(s) acos, acosh, asin, asinh, atan, atan2, atanh, cbrt, ceil, comb, copysign, cos, cosh, degrees, dist, e, erf, erfc, exp, exp2, expm1, fabs, factorial, floor, fma, fmod, frexp, fsum, gamma, gcd, hypot, inf, isclose, isfinite, isinf, isnan, isqrt, lcm, ldexp, lgamma, log, log10, log1p, log2, modf, nan, nextafter, perm, pow, prod, radians, remainder, sin, sinh, sqrt, sumprod, tan, tanh, tau, trunc and ulp from wildcard import of math (unused-wildcard-import)
-----------------------------------
Your code has been rated at 0.00/10
pyflakes output
code_with_lint.py:1:1: 'io' imported but unused
code_with_lint.py:2:1: 'from math import *' used; unable to detect undefined names
code_with_lint.py:13:5: local variable 'some_global_var' is assigned to but never used
code_with_lint.py:40:44: 'pi' may be undefined, or defined from star imports: math
code_with_lint.py:40:9: local variable 'list_comprehension' is assigned to but never used
code_with_lint.py:41:16: local variable 'time' defined in enclosing scope on line 5 referenced before assignment
code_with_lint.py:41:9: local variable 'time' is assigned to but never used
code_with_lint.py:43:9: local variable 'date_and_time' is assigned to but never used
pycodestyle output
code_with_lint.py:9:1: E302 expected 2 blank lines, found 1
code_with_lint.py:14:15: E225 missing whitespace around operator
code_with_lint.py:19:1: E302 expected 2 blank lines, found 1
code_with_lint.py:20:80: E501 line too long (80 > 79 characters)
code_with_lint.py:25:10: E711 comparison to None should be 'if cond is not None:'
code_with_lint.py:27:25: E703 statement ends with a semicolon
code_with_lint.py:31:23: E275 missing whitespace after keyword
code_with_lint.py:31:24: E201 whitespace after '('
code_with_lint.py:35:1: E302 expected 2 blank lines, found 1
code_with_lint.py:37:58: E251 unexpected spaces around keyword / parameter equals
code_with_lint.py:37:60: E251 unexpected spaces around keyword / parameter equals
code_with_lint.py:38:28: E221 multiple spaces before operator
code_with_lint.py:38:31: E222 multiple spaces after operator
code_with_lint.py:39:22: E221 multiple spaces before operator
code_with_lint.py:39:31: E222 multiple spaces after operator
code_with_lint.py:40:80: E501 line too long (83 > 79 characters)
code_with_lint.py:44:15: W292 no newline at end of file
pydocstyle output
code_with_lint.py:1 at module level:
D100: Missing docstring in public module
code_with_lint.py:10 in public function `multiply`:
D200: One-line docstring should fit on one line with quotes (found 3)
code_with_lint.py:10 in public function `multiply`:
D400: First line should end with a period (not 's')
code_with_lint.py:10 in public function `multiply`:
D401: First line should be in imperative mood; try rephrasing (found 'This')
code_with_lint.py:20 in public function `is_sum_lucky`:
D205: 1 blank line required between summary line and description (found 0)
code_with_lint.py:20 in public function `is_sum_lucky`:
D400: First line should end with a period (not 'y')
code_with_lint.py:20 in public function `is_sum_lucky`:
D401: First line should be in imperative mood; try rephrasing (found 'This')
code_with_lint.py:35 in public class `SomeClass`:
D101: Missing docstring in public class
code_with_lint.py:37 in public method `__init__`:
D107: Missing docstring in __init__