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Diffstat (limited to 'doc/src/declarative/extending.qdoc')
| -rw-r--r-- | doc/src/declarative/extending.qdoc | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/doc/src/declarative/extending.qdoc b/doc/src/declarative/extending.qdoc index c1c7547ec2..385469c29f 100644 --- a/doc/src/declarative/extending.qdoc +++ b/doc/src/declarative/extending.qdoc @@ -252,7 +252,7 @@ In particular, QML currently supports: \o \c {QList<int>} \o \c {QList<qreal>} \o \c {QList<bool>} - \o \c {QList<QString>} + \o \c {QList<QString>} and \c{QStringList} \o \c {QList<QUrl>} \endlist @@ -274,6 +274,27 @@ modified directly. Other sequence types are not supported transparently, and instead an instance of any other sequence type will be passed between QML and C++ as an opaque QVariantList. +\bold {Important Note:} There are some minor differences between the semantics of such +sequence Array types and default JavaScript Array types which result from the use of a +C++ storage type in the implementation. In particular, deleting an element from an Array +will result in a default-constructed value replacing that element, rather than an +Undefined value. Similarly, setting the length property of the Array to a value larger +than its current value will result in the Array being padded out to the specified length +with default-constructed elements rather than Undefined elements. + +The default-constructed values for each sequence type are as follows: +\table +\row \o QList<int> \o integer value 0 +\row \o QList<qreal> \o real value 0.0 +\row \o QList<bool> \o boolean value \c {false} +\row \o QList<QString> and QStringList \o empty QString +\row \o QList<QUrl> \o empty QUrl +\endtable + +If you wish to remove elements from a sequence rather than simply replace them with default +constructed values, do not use the indexed delete operator ("delete sequence[i]") but instead +use the \c {splice} function ("sequence.splice(startIndex, deleteCount)"). + \section1 Inheritance and Coercion \snippet examples/declarative/cppextensions/referenceexamples/coercion/example.qml 0 |