Code Smells

Data Clump

Data clumps are sets of related primitives (eg. 1, 3.14, "Hello", False) that always appear together. Data Clumps can be avoided by encapsulating them together in a class.

from math import sqrt

# Code smell
x_coordinate = 4
y_coordinate = -7
z_coordinate = 43

distance = sqrt(x_coordinate**2 + y_coordinate**2 + z_coordinate**2)  # Pythagorean theorem
print(distance)

# Improved
class Coordinates:
    def __init__(self, x_coordinate, y_coordinate, z_coordinate):
        self.x_coordinate = x_coordinate
        self.y_coordinate = y_coordinate
        self.z_coordinate = z_coordinate
    
    def distance(self):
        return sqrt(self.x_coordinate**2 + self.y_coordinate**2 + self.z_coordinate**2)  # Pythagorean theorem


my_coordinates = Coordinates(4, -7, 43)
print(my_coordinates.distance())

The problem with Data Clumps, is that it is not easy to centrally control their behaviour. In the example above, if we wanted to restrict y_coordinate to positive numbers only, we may need to edit the code in many places, leading to Shotgun Surgery.

Data Clumps are also often Primitive Obsessions.