Code Smell 12 - Null

Null is schizophrenic and does not exist in real world. His creator regretted and programmers around the world suffer it. Don't be a part of it.

10 October, 2022

Contributors

Maxi Contieri

@mcsee

Programmers use Null as different flags. It can hint an absence, an undefined value, en error etc. Multiple semantics lead to coupling and errors.

TL;DR: Null is schizophrenic and does not exist in real world. His creator regretted and programmers around the world suffer it. Don't be a part of it.

Problems

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Coupling among the callers and the senders.

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Mismatch among the callers and the senders.

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If/Switch/Case Polluting.

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Null is not polymorphic with real objects. Hence, Null Pointer Exception

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Null does not exist on real world. Thus, it violates Bijection Principle

Solutions

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Avoid Null.

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Use NullObject pattern to avoid ifs.

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Use Optionals.

https://www.showwcase.com/show/16232/null-the-billion-dollar-mistake

Sample Code

Wrong

Right

Detection

Most Linters can show null usages and warn us.

Exceptions

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APIs, Databases and external systems where NULL does exist.

Conclusion

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Null is the billion-dollar mistake. Yet, most program languages support them and libraries suggest its usage.

More info

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Null: The Billion-Dollar Mistake

Credits

Photo by Kurt Cotoaga on Unsplash

I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.

Tony Hoare

https://www.showwcase.com/show/16157/software-engineering-great-quotes

This article is part of the CodeSmell Series.

https://maximilianocontieri.com/how-to-find-the-stinky-parts-of-your-code

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