[Development] RFC: Proposal for a semi-radical change in Qt APIs taking strings

[Marc Mutz]

On Monday 19 October 2015 21:56:54 Smith Martin wrote:
> >This API here simply cannot exist because the returned value would be a 
> >dangling reference.
> 
> I don't understand. Implicit for using the QStringView data() function is
> knowing that once the QByteArray is set, it is never changed. Then the
> data() function is ok, isn't it?

A QStringView points to QChar* (or ushort*) while a QByteArray only provides 
char*. The fromLatin1() (say) call thus necessary will create a temporary 
QString, which will bind to the returned QStringView, but will already be 
destroyed (taking the data QStringView references with it) when control 
returns to the caller.

This particular mistake is easy to prevent statically, though:

   QStringView(QString &&) = delete;

Thanks,
Marc

-- 
Marc Mutz <marc.mutz at kdab.com> | Senior Software Engineer
KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company
Tel: +49-30-521325470
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