[Development] How to make a fancy QMap c++17 initializer_list

[Henry Skoglund]

On 2017-07-24 16:53, Thiago Macieira wrote:
> On Monday, 24 July 2017 00:00:36 PDT Marc Mutz wrote:
>> Hi,
>>
>> We haven't added deduction guides to any Qt class, yet. If you want to
>> use bleeding-edge C++, use C++, iow: std::map.
> 
> std::map currently (GCC 7.1.1) works less well than QMap, since you can't even
> trick it. The std::pair that std::map uses requires a const Key, which you
> can't get with a primitive prvalue.
> 

Tested a bit more, here's the current best effort for both maps 
(yielding 12 words from Pres. Lincoln) and indeed Qt is ahead in this 
game (std::map requires more handholding):

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#include "qapplication.h"
#include "qmap.h"
#include "map"
#include "qdebug.h"

int main(int argc, char *argv[])
{
     QApplication a(argc, argv);

     QMap m1 = {std::pair{2,"score"}, {4,"seven"}, {1,"Four"}, 
{5,"years"}, {3,"and"}, {6,"ago"}};
     std::map m2 = {std::pair<const int,QString>{8,"fathers"}, 
{10,"forth"}, {7,"our"}, {11,"on"}, {9,"brought"}, {12,"this"}};

     for (auto v : m1)
         qDebug() << v;

     for (auto v : m2)
         qDebug() << v.second;
}

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