Functions, methods, or lambdas with a long parameter list are difficult to use, as maintainers must figure out the role of each parameter and keep
track of their position.
def set_coordinates(x1, y1, z1, x2, y2, z2): # Noncompliant
# ...
The solution can be to:
- Split the function, method, or lambda into smaller ones
# Each function does a part of what the original set_coordinates function was doing, so confusion risks are lower
def set_origin(x, y, z):
# ...
def set_size(width, height, depth):
# ...
- Find a better data structure for the parameters that group data in a way that makes sense for the specific application domain
@dataclass
class Point: # In geometry, Point is a logical structure to group data
x: int
y: int
z: int
def set_coordinates(p1: Point, p2: Point):
# ...
This rule raises an issue when a function, a method, or a lambda has more parameters than the provided threshold.
Exceptions
The first argument of non-static methods, i.e., self or cls, is not counted as it is mandatory and passed
automatically.
