Mathias Hasselmann schreef op 8-2-2015 om 22:28:
Am 08.02.2015 um 14:28 schrieb Marc Mutz:
c. Using QMap. As Alex Stepanov put it: every use of a map should be discussed
in a face-to-face meeting with your manager. Since we don't have that, I'd
change this to: Everyone wishing to use a QMap should implement one before
using it for the first time. Then you'd see what you inflict on the world.
In the vast majority of cases, a sorted vector is much faster, due to
locality-of-reference. A RB-tree is optimized for wildly mixing insertions,
lookups, and removals. When you can batch updates and separate them from
lookups, time-wise, then a sorted vector is usually preferrable.
I totally agree, thank you for raising this. Sadly a sorted vector isn't
as convenient to use as a map. Maybe there should some convenience API
added, Or does it exist already and I am just too ignorant to know it?
How about this?
|template< typename T>
typename std::vector<T>::iterator
insert_sorted( std::vector<T> & vec, Tconst& item)
{
return vec.insert
(
std::upper_bound( vec.begin(), vec.end(), item),
item
);
}|
(from http://stackoverflow.com/a/25524075/2151404)
Something like this should work just as well on QVector, right? If you
are doing multiple inserts, perhaps you should keep the inserts outside
the main vector while you make them, and only at the end do a single
std::merge.
André
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