[Development] Upgrading the sources to C++11 keywords (Q_NULLPTR, etc.)

Julien Blanc julien.blanc at nmc-company.com
Tue Feb 10 17:08:55 CET 2015

On 10/02/2015 16:33, Knoll Lars wrote:
> IMO there’s simply too many questions that this one example doesn’t answer
> to conclude that what we are doing is bad.

Two arguments :
- implicit sharing is convenient, and really developer friendly. It is 
probably a good idea since strings are really present a lot in signals 
and slots (and afaik, passed by value in these context)
- implicit sharing is implicit, you don’t have the choice not to pay for 
it, which is a bad thing.

 From my experience, QStrings are slow. About two times slower than 
using plain std::string in our use cases, but the culprit for this 
slowness is, as far as we know, the internal 16 bits encoding, whereas 
our data sources are all using utf-8. We have no evidence that the 
implicit sharing cost is significant or not.

Now the question is, is there some simple way to disable QString (and 
eventually other data structures) implicit sharing to make some real 
world benchmarks ?


Julien Blanc

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