QMetaSequence::Iterable Class

class QMetaSequence::Iterable

The QMetaSequence::Iterable class is an iterable interface for a container in a QVariant. More...

This class was introduced in Qt 6.11.

Public Types

Public Functions

QVariant at(qsizetype idx) const
void setAt(qsizetype idx, const QVariant &value)

Detailed Description

This class allows several methods of accessing the values of a container held within a QVariant. An instance of QMetaSequence::Iterable can be extracted from a QVariant if it can be converted to a QVariantList, or if the container it contains is registered using Q_DECLARE_SEQUENTIAL_CONTAINER_METATYPE. Most sequential containers found in Qt and some found in the C++ standard library are automatically registered.

 QList<int> intList = {7, 11, 42};

 QVariant variant = QVariant::fromValue(intList);
 if (variant.canConvert<QVariantList>()) {
     QMetaSequence::Iterable iterable = variant.value<QMetaSequence::Iterable>();
     // Can use C++11 range-for:
     for (const QVariant &v : iterable) {
         qDebug() << v;
     }
     // Can use iterators:
     QMetaSequence::Iterable::const_iterator it = iterable.begin();
     const QMetaSequence::Iterable::const_iterator end = iterable.end();
     for ( ; it != end; ++it) {
         qDebug() << *it;
     }
 }

The container itself is not copied before iterating over it.

See also QVariant.

Member Type Documentation

[alias] Iterable::BidirectionalConstIterator

Exposes a const_iterator using std::bidirectional_iterator_tag.

[alias] Iterable::BidirectionalIterator

Exposes an iterator using std::bidirectional_iterator_tag.

[alias] Iterable::ForwardConstIterator

Exposes a const_iterator using std::forward_iterator_tag.

[alias] Iterable::ForwardIterator

Exposes an iterator using std::forward_iterator_tag.

[alias] Iterable::InputConstIterator

Exposes a const_iterator using std::input_iterator_tag.

[alias] Iterable::InputIterator

Exposes an iterator using std::input_iterator_tag.

[alias] Iterable::RandomAccessConstIterator

Exposes a const_iterator using std::random_access_iterator_tag.

[alias] Iterable::RandomAccessIterator

Exposes an iterator using std::random_access_iterator_tag.

Member Function Documentation

QVariant Iterable::at(qsizetype idx) const

Returns the value at position idx in the container.

Note: If the underlying container does not provide a native way to retrieve an element at an index, this method will synthesize the access using iterators. This behavior is deprecated and will be removed in a future version of Qt.

See also setAt().

void Iterable::setAt(qsizetype idx, const QVariant &value)

Sets the element at position idx in the container to value.

See also at().