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phpexceptiontry-catch-finally

When and why can `finally` be useful?


PHP 5.5 has implemented finally to try-catch. My doubt is: when exactly try-catch-finally that might be more helpful than just I write below try-catch?

Example, difference between:

try { something(); }
catch(Exception $e) { other(); }
finally { another(); }

Instead of, just:

try { something(); }
catch(Exception $e) { other(); }
another();

Can send me some example that is common to this case?

Notes:

  1. I talk about try-catch-finally, and not about try-finally, only;
  2. There are some "features" cool, like you cancel current exception and throw a new-other-exception on finally (I don't tried, I read here). I don't know if it is possible without finally;
  3. Would not be more useful something like notcatch? So I can run a code if try goes without an exception. hehe

Solution

  • The code within the finally block is always executed after leaving from either try or catch blocks. Of course you may continue writing code after the try-catch and it will be executed as well. But finally could be useful when you'd like to break out of code execution (such as returning from a function, breaking out of a loop etc.). You can find some examples on this page - https://www.php.net/exceptions, such as:

    function example() {
      try {
         // open sql connection
         // Do regular work
         // Some error may happen here, raise exception
      }
      catch (Exception $e){
        return 0;
        // But still close sql connection
      }
      finally {
        //close the sql connection
        //this will be executed even if you return early in catch!
      }
    }
    

    But yes, you are right; finally is not very popular in everyday use. Certainly not as much as try-catch alone.