[QGIS-Developer] [Qgis-developer] Min Qt version

[Martin Dobias]

Hi Radim

On Tue, May 30, 2017 at 4:11 PM, Radim Blazek <radim.blazek at gmail.com> wrote:
> On Thu, May 25, 2017 at 10:53 AM, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>>> What min version of Qt are you able to compile with? We should update INSTALL.
>>>
>>> In INSTALL requirements it is also written: Qwt >= 5.0 & (< 6.1 with
>>> internal QwtPolar)
>>> but Qwt 6.0 does not compile with Qt >= 5.4:
>>> http://www.qtcentre.org/archive/index.php/t-63275.html
>>> Is it still true that Qwt must be < 6.1? I have compiled with 6.1.3
>>> (but not tested related functionality).
>>
>> I can't help with minimum Qt version (it's either 5.4 or 5.5, but I
>> don't believe a firm decision has been made), but the minimum Qwt is
>> 6.1. In this case the INSTALL is incorrect and needs to be updated.
>
> I have updated INSTALL to:
> Qt >= 5.4.0
> Qwt >= 6.1
>
> Just for curiosity, question for C++ experts, how this can compile/work:
>     QStringList lineParts = part.split( linePartRx, QString::SkipEmptyParts );
>     label = lineParts.mid( 5 ).join( ' ' );
> if mid() returns QList<QString> which has no join()?

QStringList has a constructor taking const QList<QString> & as an
argument - that is an implicit conversion constructor (it has one
argument and it is not declared as "explicit"), so it allows C++ to
silently convert QList<QString> to QStringList and call
QStringList::join().

Cheers
Martin