Problem with that

"It's not an error. It's just a null response, meaning it didn't find anything."

If its not an error, then don't throw and exception. If it is an error, then do throw an exception.

You can't decide if something is an error until you know the purpose of the function you are writing. If the purpose is "Find the index", then not finding is an error. If the purpose is "Find the index if it exists", then not finding it is not an error.

Both choices make sense. Pick the one that makes sense to you at this moment. If you pick wrong, then let me tell you about a little thing called refactoring.

I remember working on a library that had open and close methods. I decided to make it an error to close an already closed connection (i.e. the purpose was "Close an open connection"). After writing some code using it, I discovered that it complicated my client logic testing to see if something was really open before attempting to close it. I changed the function to mean "Make sure the connection is closed", and the client code got significantly simpler.

Post #199,289 by drewk 3/17/05 6:13:50 PM Reply	Problem with that "It's not an error. It's just a null response, meaning it didn't find anything." I hear it already. === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #199,292 by ben_tilly 3/17/05 6:19:06 PM Reply	See? Whether it is an error IS ambiguous! I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #199,296 by drewk 3/17/05 6:28:16 PM Reply	I think I know what to do then My first instinct was to say you return errors or throw exceptions, but not both. I wasn't able to articulate a good reason for it though. But your formulation works for me: An exception is a language-specific mechanism for handling errors. If I start from that, there isn't any reason to use both interchangeably. === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #199,300 by ben_tilly 3/17/05 6:59:56 PM Reply	Exactly I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #199,332 by JimWeirich 3/17/05 11:59:18 PM Reply	Re: Problem with that "It's not an error. It's just a null response, meaning it didn't find anything." If its not an error, then don't throw and exception. If it is an error, then do throw an exception. You can't decide if something is an error until you know the purpose of the function you are writing. If the purpose is "Find the index", then not finding is an error. If the purpose is "Find the index if it exists", then not finding it is not an error. Both choices make sense. Pick the one that makes sense to you at this moment. If you pick wrong, then let me tell you about a little thing called refactoring. I remember working on a library that had open and close methods. I decided to make it an error to close an already closed connection (i.e. the purpose was "Close an open connection"). After writing some code using it, I discovered that it complicated my client logic testing to see if something was really open before attempting to close it. I changed the function to mean "Make sure the connection is closed", and the client code got significantly simpler. -- -- Jim Weirich jim@weirichhouse.org [link\|http://onestepback.org\|http://onestepback.org] --------------------------------------------------------------------- "Beware of bugs in the above code; I have only proved it correct, not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)

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