On 28/04/2020 03.56, Giuseppe D'Angelo via Development wrote:
1) First and foremost, in Qt 6 QString, QByteArray, QVector, are bigger
than a pointer (3 times a pointer size). So, in Qt 6:
* either QList stays unchanged, and now we heap allocate each element
for those cases too (thus it's necessary to know how the above
statistics change); or
* QList gets adapted so that its internal array allocates 3 *
sizeof(void*) per element, so that e.g. Q6StringList won't require a
per-item allocation. This would then also avoid allocations for other
datatypes, e.g. QStringView, QImage, maybe QVariant and QColor; but of
course waste a ton of space for the ones which remain small (most of Qt
implicitly shared datatypes).
Uh... can't it allocate sizeof(T) if T meets some criteria? IOW, I don't
see the second case penalizing smaller types unless the implementation
is poorly done.
--
Matthew
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