Why not use exceptions as regular flow of control?

Question

To avoid all standard-answers I could have Googled on, I will provide an example you all can attack at will.

C# and Java (and too many others) have with plenty of ty

Answer 1

If you are using exception handlers for control flow, you are being too general and lazy. As someone else mentioned, you know something happened if you are handling processing in the handler, but what exactly? Essentially you are using the exception for an else statement, if you are using it for control flow.

If you don't know what possible state could occur, then you can use an exception handler for unexpected states, for example when you have to use a third-party library, or you have to catch everything in the UI to show a nice error message and log the exception.

However, if you do know what might go wrong, and you don't put an if statement or something to check for it, then you are just being lazy. Allowing the exception handler to be the catch-all for stuff you know could happen is lazy, and it will come back to haunt you later, because you will be trying to fix a situation in your exception handler based on a possibly false assumption.

If you put logic in your exception handler to determine what exactly happened, then you would be quite stupid for not putting that logic inside the try block.

Exception handlers are the last resort, for when you run out of ideas/ways to stop something from going wrong, or things are beyond your ability to control. Like, the server is down and times out and you can't prevent that exception from being thrown.

Finally, having all the checks done up front shows what you know or expect will occur and makes it explicit. Code should be clear in intent. What would you rather read?