HighFile-scopePython Plug & play

Avoid Confusing Implicit String Concatenation

Detect missing commas in lists, tuples, or dictionaries that unintentionally concatenate strings. This can lead to unexpected behavior and hard-to-find bugs.

Add to Mesrai Open workspace

Why this matters

Accidental string concatenation can happen when missing commas in lists, tuples, or dictionaries, leading to unexpected bugs.

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

def func():
    return "item1" "item2"  # Noncompliant: a comma is missing to return a tuple.

["1"  # Noncompliant: a comma is missing.
 "2",
 "a very"  # Noncompliant: a "+" is missing.
 "long string"]

Prefer

def func():
    return "item1", "item2"

["1",
 "2",
 "a very" +
 "long string"]

More snippets

Bad

def func():
    return "item1" "item2"  # Noncompliant: a comma is missing to return a tuple.

["1"  # Noncompliant: a comma is missing.
 "2",
 "a very"  # Noncompliant: a "+" is missing.
 "long string"]

Good

def func():
    return "item1", "item2"

["1",
 "2",
 "a very" +
 "long string"]

Related rules

From the same buckets as this rule.

Critical
Avoid equality operators in loop termination conditions
Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.
error-handlingreadability-refactor
Critical
Avoid Returning Null in Non-Async Task Methods
Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.
error-handlingreadability-refactor+1
Critical
Avoid Using Boolean Expressions in `except` Statements
Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.
error-handlingstack-python

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

def func():
    return "item1" "item2"  # Noncompliant: a comma is missing to return a tuple.

["1"  # Noncompliant: a comma is missing.
 "2",
 "a very"  # Noncompliant: a "+" is missing.
 "long string"]

Prefer

def func():
    return "item1", "item2"

["1",
 "2",
 "a very" +
 "long string"]

More snippets

Bad

def func():
    return "item1" "item2"  # Noncompliant: a comma is missing to return a tuple.

["1"  # Noncompliant: a comma is missing.
 "2",
 "a very"  # Noncompliant: a "+" is missing.
 "long string"]

Good

def func():
    return "item1", "item2"

["1",
 "2",
 "a very" +
 "long string"]

Related rules

From the same buckets as this rule.

Critical

Avoid equality operators in loop termination conditions

Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.

error-handlingreadability-refactor

Critical

Avoid Returning Null in Non-Async Task Methods

Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.

error-handlingreadability-refactor+1

Critical

Avoid Using Boolean Expressions in `except` Statements

Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.

error-handlingstack-python