On 6/23/2010 11:01 AM, Eric Niebler wrote:
On 6/23/2010 6:12 AM, Daniel James wrote:
On 23 June 2010 03:49, Rob Stewart <robertstewart@comcast.net> wrote:
I quickly chose to throw std::logic_error from unquoted() when it fails to find a closing delimiter. There may well be a better approach; feel free to suggest alternatives.
You should inherit from std::runtime_error, since that would be usually caused by bad input rather than programmer error.
Bad input can be a programmer error too. Here's how you decide:
- Decide if passing a malformed string is a violation of unquote's preconditions. - If it is, throw something derived from logic_error.
I mean, assert, not throw. Sigh, bitten by C++'s weird exception hierarchy again. logic_error is useless because it derives from std::exception, which people catch all over the place. A precondition violation is not recoverable.
- If not, handle it gracefully or, if you cannot, throw something derived from runtime_error.
Users can (in theory) check that the string is well-formed before calling unquote, but to do so they would essentially have to implement unquote themselves. So making it a precondition that the input is well-formed seems onerous in this case. I would not make it a precondition; instead, I would accept it as valid input and document that.
For valid input, I would prefer if unquote found a way to muddle through and do something reasonable. Throwing an exception when a trailing quote is missing seems like smacking someone's hand when they forgot to say "mother may I?" Why not just accept it? And document that fact! If the string is malformed in a way that you really can't muddle on, then throw something derived from runtime_error.
-- Eric Niebler BoostPro Computing http://www.boostpro.com