on Sat Oct 15 2011, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:
Dave Abrahams wrote:
on Fri Oct 14 2011, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:
try { do some push_backs into a static_vector; we don't know how many } catch( out_of_capacity& ) { // ignore, what we gathered so far is good enough for gov't use }
Yes, it's possible, but highly unusual, for someone to use the class that way.
I'm not sure of that either. What makes you think so?
a. It's not an idiom typically used with C++ b. It's very inefficient in a context where we're surely trying to optimize (otherwise why use StaticVector?) I also want to add that the above code would be broken and wrong if you were using vector instead of static_vector, unless you know the number of possible push_backs is bounded.
What are the "proper" uses for it?
It sounds like you're asking me to prove something for which we both know there's no proof. If you design the class to throw exceptions when the fixed capacity is exceeded, your code above is perfectly "proper." The problem is that once we get a step away from the call site, we can't tell wether the usage was proper anymore. If we can figure out how to get cars to bounce harmlessly out of collisions we could decide to make it legal to ignore stop signs and just count on the bounce to handle it. Should we? It would then be impossible to yank the out-of-control drivers off the road, and if people start taking advantage of this protection, it's going to slow down traffic. If instead we can capture colliding drivers and send them to driving school, isn't that better? -- Dave Abrahams BoostPro Computing http://www.boostpro.com