On 08/07/2021 08:41, Oliver Knoll wrote:
template<typename K, typename V> static QVector<K> keysToVector(QHash<K,V> const& hash) { QVector<K> v; v.reserve(hash.size()); for (auto it = hash.keyBegin(); it != hash.keyEnd(); ++it) v.append(*it); return v; } QVector<int> CompatibilityInterfaceImpl::getActionIds() const { return keysToVector(_actions); }Dear all, I am sorry to kind of hijack this thread with a follow-up question, but I am trying to better understand what‘s going on „under the C++ hood“, especially given the solution above. When we look at the original code again: QVector<int> CompatibilityInterfaceImpl::getActionIds() const { return _actions.keys().toVector(); // _actions is a QHash } And the warning it generates: allocating an unneeded temporary container [clazy-container-anti-pattern]
What clazy is warning about here is the, temporary intermediate, container created by QHash::keys(), this creates a QList of keys (which is then converted to a QVector). What's more efficient is to iterate right over the QHash itself, and use iterator.key() to fill the vector.
[...] -- Ahmad Samir _______________________________________________ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
