Code Smell 56 - Preprocessors

Code Smell 56 - Preprocessors

Maxi Contieri
·Jan 18, 2021·

2 min read

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We want our code to behave different on different environments, operating systems, so taking decisions at compile time is the best decision, isn't it?.

Problems

  • Readability

  • Premature Optimization

  • Unnecessary complexity

  • Debugging

Solutions

  1. Remove all compiler directives.

  2. If you want different behavior, model it with objects

  3. If you think there's a performance penalty, make a serious benchmark instead of doing premature optimization.

Sample Code

Wrong

#if VERBOSE >= 2
  printf("trace message");
#endif
if (runtimeEnvironment->traceDebug()){
  printf("trace message");
}

## even better with polymorphism and we avoid annoying ifs

runtimeEnvironment->traceDebug("trace message");

Detection

This is a syntactic directive promoted by several languages, therefore it is easy to detect and replace with real behavior.

Tags

  • Compilers

  • Metaprogramming

Conclusion

Adding an extra layer of complexity makes debugging very difficult. This technique was used when memory and CPU were scarce. Nowadays, we need clean code and we must leave premature optimization buried in the past.

Bjarne Stroustrup, in his book The Design and Evolution of C++, regrets on the pre-processor directives he created years before.

Relations

More info

#ifdef Considered Harmful

Credits

Photo by CDC on Unsplash


C++ is designed to allow you to express ideas, but if you don't have ideas or don't have any clue about how to express them, C++ doesn't offer much help.

Bjarne Stroustrup



This article is part of the CodeSmell Series.

 
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Technical Opinions are my own. I don't have the revealed truth.

Software Design is a creative activity. These are hints and not rigid rules.

I write on BackEnd Business Systems and OOP Design. My advice/experience might not suit other systems.

You can write me at info(at)maximilianocontieri.com