On Wednesday, March 21, 2012 20:46:05 Jonathan M Davis wrote: > On Wednesday, March 21, 2012 20:17:06 Steven Schveighoffer wrote: > > On Wed, 21 Mar 2012 19:56:41 -0400, Jonathan M Davis <jmdavisp...@gmx.com> > > > > wrote: > > > Except that containers shouldn't provide indexing if it's not efficient. > > > And > > > from what I've seen, it's far too common for programmers to check length > > > == 0, > > > and they end up doing it on stuff like linked lists where it _is_ > > > inefficient. > > > > Wait, if someone provides inefficient length, what makes you think they > > won't provide inefficient indexing? > > Both C++'s STL and D's std.container put requirements on the algorithmic > complexity of various operations. O(n) indexing would violate them, whereas > they allow O(n) length/size.
Actually, it looks like std.container _does_ guarantee that length is O(1), unlike C++'s STL, in which case it's not the same issue that it is in C++. I'd still tend to argue that checking for empty is better, but I guess that it's not as big a deal. In C++, it's a definite problem when programmers keep checking that size() == 0, since inevitably, it ends up happening with linked lists and the like, making for inefficient code, and simply being in the habit of using empty() rather than size() == 0 avoids such problems. - Jonathan M Davis
