DEV Community

loading...
Cover image for Code Smell 80 - Nested Try/Catch

Code Smell 80 - Nested Try/Catch

Maxi Contieri
Learn something new every day. - I am a senior software engineer working in industry, teaching and writing on software design, SOLID principles, DDD and TDD.
Originally published at maximilianocontieri.com ・2 min read

Exceptions are a great way of separating happy path versus trouble path. But we tend to over-complicate our solutions.

TL;DR: Don't nest Exceptions. Nobody cares of what you do in the inner blocks.

Problems

  • Readability

Solutions

  1. Refactor

Sample Code

Wrong

try {
    transaction.commit();
} catch (e) {
    logerror(e);
    if (e instanceOf DBError){
      try {
          transaction.rollback();
      } catch (e) {
          doMoreLoggingRollbackFailed(e);
      }
    }
}

//Nested Try catchs
//Exception cases are more important than happy path
//We use exceptions as control flow
Enter fullscreen mode Exit fullscreen mode

Right

try {
    transaction.commit();
} catch (transactionError) {
    this.withTransactionErrorDo(transationError, transaction);
}

//transaction error policy is not defined in this function
//so we don't have repeated code
//code is more readable
//It is up to the transaction and the error to decide what to do
Enter fullscreen mode Exit fullscreen mode

Detection

We can detect this smell using parsing trees.

Tags

  • Exceptions

Conclusion

Don't abuse exceptions, don't create Exception classes no one will ever catch, and don't be prepared for every case (unless you have a good real scenario with a covering test).

Happy path should always be more important than exception cases.

Relations

More Info

Credits

Photo by David Clode on Unsplash

Thanks to @Rodrigo for his inspiration


Writing software as if we are the only person that ever has to comprehend it is one of the biggest mistakes and false assumptions that can be made.

Karolina Szczur


This article is part of the CodeSmell Series.

Discussion (0)