[Development] Should QVariant be doing fuzzy comparisons on doubles?

Marc Mutz marc.mutz at kdab.com
Mon Sep 19 18:48:10 CEST 2016

On Monday 19 September 2016 18:20:48 Thiago Macieira wrote:
> Should we do fuzzy comparisns in QVariant?

If you talk about op==, then using fuzzy compare is a definite no-no, because 
it makes it impossible to define a hash function.

Fuzzy comparision should be performed with a named function, qFuzzyCompare, 
and _only_ with that function.

We need to fix other classes for Qt 6, too (e.g. Q(Size|Point|Line)F.

That said, a qFuzzyCompare(QVariant, QVariant) would probably be useful, but 
requires extensive extra work, like hashing a QVariant, too.


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

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