# Code Smell 80 - Nested Try/Catch

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

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

# Problems

* Readability
    

# Solutions

1. Refactor
    

# Sample Code

## Wrong

```javascript
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 the happy path
// We use exceptions as control flow
```

## Right

```javascript
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
```

# 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).

The happy path should always be more important than exception cases.

# Relations

%[https://maximilianocontieri.com/code-smell-73-exceptions-for-expected-cases] 

%[https://maximilianocontieri.com/code-smell-26-exceptions-polluting] 

# More Info

* [Nested Try/Catchs](https://beginnersbook.com/2013/04/nested-try-catch/)
    

# Credits

Photo by [David Clode](https://unsplash.com/@davidclode) on [Unsplash](https://unsplash.com/s/photos/fishing-net)

Thanks to @[Rodrigo](@rodrigomd) for his inspiration

%[https://twitter.com/_rodrigomd/status/1403359513965731843] 

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> 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*

%[https://maximilianocontieri.com/software-engineering-great-quotes] 

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This article is part of the CodeSmell Series.

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