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Forbid tuples without parenthesis

See original GitHub issue

Rule request

Thesis

# bad
a = 1, 2

# good
a = (1, 2)

Reasoning

It shocked me to learn that in Python tuples are defined by commas and not parenthesis. This rule request will find a very likely bug that is a = 1,, a one element tuple. Also it improves readability.

Issue Analytics

State:
Created 2 years ago
Comments:5 (5 by maintainers)

Top GitHub Comments

1reaction

sobolevncommented, Jan 10, 2022

The AST is identical for these two cases:

>>> import ast
>>> code1 = 'a = (1, 2)'
>>> code2 = 'a = 1, 2'
>>> for node in ast.walk(ast.parse(code1)):
...    print(ast.dump(node))
... 
Module(body=[Assign(targets=[Name(id='a', ctx=Store())], value=Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load()))], type_ignores=[])
Assign(targets=[Name(id='a', ctx=Store())], value=Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load()))
Name(id='a', ctx=Store())
Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load())
Store()
Constant(value=1)
Constant(value=2)
Load()

>>> for node in ast.walk(ast.parse(code2)):
...    print(ast.dump(node))
... 
Module(body=[Assign(targets=[Name(id='a', ctx=Store())], value=Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load()))], type_ignores=[])
Assign(targets=[Name(id='a', ctx=Store())], value=Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load()))
Name(id='a', ctx=Store())
Tuple(elts=[Constant(value=1), Constant(value=2)], ctx=Load())
Store()
Constant(value=1)
Constant(value=2)
Load()

So you either need: