Hi,
I think there are almost no need for deduction guides, for example a
similar program using QVector compiles fine on gcc-7:
--------------------------------------------------------------
#include "qapplication.h"
#include "qvector.h"
#include "qdebug.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QVector vec = {"Now", "is", "the", "time", "for", "all"};
for (auto v : vec)
qDebug() << v;
}
--------------------------------------------------------------
It's just QMap that I got stuck on, but as you say, it's very bleeding
edge, mostly for showing off :-)
/Henry
On 2017-07-24 09:00, 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.
Patches welcome, bug reports accepted.
Thanks,
Marc
On 2017-07-24 06:32, Henry Skoglund wrote:
Hello, I've been testing more C++17 class template auto deduction
awith gcc-7, and got stuck on QMap, consider this simple test program:
-------------------------------------------------------------
#include "qapplication.h"
#include "qmap.h"
#include "qdebug.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QMap m = {std::pair{2,"score"}, {4,"seven"}, {1,"Four"},
{5,"years"}, {3,"and"}, {6,"ago"}};
for (auto v : m)
qDebug() << v;
}
-------------------------------------------------------------
I really would like to just write a {{Key,T}..} list but it will not
compile. As a kludge/compromise it works if I write "std::pair" around
the first {} pair, to force the compiler to see it my way. Then the
speech of Mr. Lincoln comes out fine.
In C++17 you should be able to fix this through a "User-defined
deduction guide" to help the compiler. I've been trying various
template one-liners but alas, I think my brain is too small. Anyone
got a clue?
Rgrds Henry
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