Code Smell 24 - Boolean Coercions

Booleans should be just True and false

TL;DR: Don't do magic castings to boolean. You will regret on a friday night.

Problems

Hiding Errors
Accidental complexity coupled to one particular language.
Readability
Difficulty to hop among languages.
IFs

Solutions

Be explicit.
Work with booleans for boolean conditions. Not integers, not nulls, not strings, not lists. Just booleans.
Fail fast

Sample Code

Wrong

virus = ['MERS', 'SARS']
vaccines = []

if vaccines:
    print ("let's get vaccinated")
else:
    print ("We have no vaccines yet. Keep researching")

if virus:
    print ("There are some virus around. Take extra care")
else:
    print ("We are free to get out. Not masks are necessary")

#equivalent     

if not vaccines:
    print ("We have no vaccines yet. Keep researching")
else:
    print ("let's get vaccinated")

if not virus:
    print ("We are free to get out. Not masks are necessary")
else:
    print ("There are some virus around. Take extra care")

Right

if len(vaccines) == 0:
    print ("We have no vaccines yet. Keep researching")
else:
    print ("Let's get vaccinated")


if len(virus) == 0:
    print ("We are free to get out. Not masks are necessary")
else:
    print ("There are some virus around. Take extra care")

Detection

This is a language feature. Some strict languages show warnings with this magic wizardry.

Conclusion

Some languages encourage doing some magic abbreviations and automatic castings. This is a source of errors and a Premature Optimization warning.

We should always be as explicit as possible.

Relations

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More Info

Fail Fast

Maxi Contieri ・ Dec 6 '20

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It is not the language that makes programs appear simple. It is the programmer that make the language appear simple!

Robert Martin

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Maxi Contieri ・ Dec 28 '20

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This article is part of the CodeSmell Series.

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Last update: 2021/07/07