org.sonar.l10n.py.rules.python.S5607.html Maven / Gradle / Ivy
This rule raises an issue when an operator is used on incompatible types.
Why is this an issue?
For a specific operator, two types are considered incompatible if no built-in operations between those types exist and none of the operands has
implemented the operator’s corresponding special methods. Performing such an operation on incompatible types will raise a TypeError.
Calling an operator in Python is equivalent to calling a special method (except for the identity operator is). Python provides a set
of built-in operations. For example, to add two integers: 1 + 2, calling the built-in operator + is equivalent to calling
the special method __add__ on the type int.
Python allows developers to define how an operator will behave with a custom class by implementing the corresponding special method. When defining
such methods for symmetrical binary operators, developers need to define two methods so that the order of operands doesn’t matter, ex:
__add__ and __radd__.
For a complete list of operators and their methods see the Python documentation: arithmetic and bitwise operators, comparison operators.
How to fix it
Implementing the special methods for a specific operator will fix the issue.
Code examples
Noncompliant code example
class Empty:
pass
class Add:
def __add__(self, other):
return 42
Empty() + 1 # Noncompliant: no __add__ method is defined on the Empty class
Add() + 1
1 + Add() # Noncompliant: no __radd__ method is defined on the Add class
Add() + Empty()
Empty() + Add() # Noncompliant: no __radd__ method is defined on the Add class
Compliant solution
class Empty:
pass
class Add:
def __add__(self, other):
return 42
def __radd__(self, other):
return 42
Add() + 1
1 + Add()
Add() + Empty()
Empty() + Add()
Resources
Documentation