Software is about contracts and ambiguous contracts are a nightmare

TL;DR: Keep your code explicit

Problems

• Coupling

• Fail Fast Principle violation

• Bijection Fault

Solutions

1. Be declarative and explicit

2. Don't oversimplify

Context

Hidden assumptions are underlying beliefs or expectations not explicitly stated in the code.

They are still present and can impact the behavior of the software.

Various reasons can give rise to assumptions such as incomplete requirements, incorrect presumptions about the user or environment, limitations of the programming language or tools, and bad accidental decisions.

Sample Code

Wrong

tenCentimeters = 10
tenInches = 10

tenCentimeters + tenInches
# 20
# this error is based on the hidden assumption of a unit (any)
# and caused the Mars Climate Orbiter failure 

Right

class Unit:
    def __init__(self, name, symbol):
        self.name = name
        self.symbol = symbol

class Measure:
    def __init__(self, scalar, unit):
        self.scalar = scalar
        self.unit = unit

    def __str__(self):
        return f"{self.scalar} {self.unit.symbol}"

centimetersUnit = Unit("centimeters", "cm")
inchesUnit = Unit("inches", "in")

tencCentimeters = Measure(10, centimeters)
tenInches = Measure(10, inches)

tenCentimeters + tenInches
# error until we introduce a conversion factor
# in this case the conversion is constant 
# inches = centimeters / 2.54

Detection

[X] Manual

This is a design smell

Tags

• Coupling

Conclusion

Hidden assumptions can be difficult to identify and can lead to bugs, security vulnerabilities, and usability issues.

To mitigate these risks, software developers should be aware of their assumptions and biases.

Developers also need to engage with users to understand their needs and expectations.

They must test their software in various scenarios to uncover hidden assumptions and edge cases.

Relations

Code Smell 02 - Constants and Magic Numbers

Maxi Contieri ・ Oct 21 '20

#beginners #codenewbie #100daysofcode #codequality

More Info

Mars Climate Orbiter Disaster

Coupling: The one and only software design problem

Maxi Contieri ・ Feb 6 '21

#webdev #programming #oop #tutorial

Measure Solution

Disclaimer

Code Smells are my opinion.

Credits

Photo by Christian Pfeifer on Unsplash

A human organization is just as much an information system as any computer system. It is almost certainly more complex, but the same fundamental ideas apply. Things that are fundamentally difficult, like concurrency and coupling, are difficult in the real world of people, too.

Dave Farley

Software Engineering Great Quotes

Maxi Contieri ・ Dec 28 '20

#codenewbie #programming #quotes #software

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code

Maxi Contieri ・ May 21 '21

#codenewbie #tutorial #codequality #beginners