[Development] QTextStream::readLine(0) is an ambiguous overload in 5.5

Marc Mutz marc.mutz at kdab.com
Sun May 17 22:17:04 CEST 2015

On Sunday 17 May 2015 15:19:49 Giuseppe D'Angelo wrote:
> It would solve, but Qt APIs use pointers instead of references for
> out-arguments (and that's a very good code policy).

*Any* form of out parameter is bad code policy. Much better in virtually all 
cases to return multiple values in a small struct.

In the case at hand, the idea is probably to reuse the capacity of the passed 
QString, so returning a struct while still allowing reuse of the capacity 
requires C++11 (taking a QString&& to avoid a refcount > 1, which incidentally 
shows how poor pointer parameter semantics really are).

I believe it was Sean Parent who in one of his talks showed how capacity-
preserving file reading should be implemented (iirc, by keeping the string as 
a member of an object and handing it out as a reference).


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

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