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| author | Warwick Allison <warwick.allison@nokia.com> | 2010-02-23 03:43:11 (GMT) |
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| committer | Warwick Allison <warwick.allison@nokia.com> | 2010-02-23 03:43:11 (GMT) |
| commit | 7828b564d6d857307aa13e273045ac7b82fec046 (patch) | |
| tree | 654a7ee91bff0b08d710066c07cf1220e57b23de /doc/src | |
| parent | c48ce6292d52b6f0a2a0ba54109a426d33eb7842 (diff) | |
| parent | 23316b14f28eb1b135b6e8e90fa6fdb34dc39b59 (diff) | |
| download | Qt-7828b564d6d857307aa13e273045ac7b82fec046.zip Qt-7828b564d6d857307aa13e273045ac7b82fec046.tar.gz Qt-7828b564d6d857307aa13e273045ac7b82fec046.tar.bz2 | |
Merge branch 'master' of scm.dev.nokia.troll.no:qt/qt-qml
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/declarative/extending.qdoc | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/doc/src/declarative/extending.qdoc b/doc/src/declarative/extending.qdoc index 0456f3f..d3e6c14 100644 --- a/doc/src/declarative/extending.qdoc +++ b/doc/src/declarative/extending.qdoc @@ -375,6 +375,37 @@ object will only be returned if it has previously been created. \l {Extending QML - Attached Properties Example} shows the complete code used to implement the rsvp attached property. +\section1 Memory Management and QVariant types + +It is an elements responsibility to ensure that it does not access or return +pointers to invalid objects. QML makes the following guarentees: + +\list +\o An object assigned to an QObject (or QObject-derived) pointer property will be +valid at the time of assignment. + +Following assignment, it is the responsibility of the class to subsequently guard +this pointer, either through a class specific method or the generic QPointer class. + +\o An object assigned to a QVariant will be valid at the time of assignment. + +When assigning an object to a QVariant property, QML will always use a QMetaType::QObjectStar +typed QVariant. It is the responsibility of the class to guard the pointer. A +general rule when writing a class that uses QVariant properties is to check the +type of the QVariant when it is set and if the type is not handled by your class, +reset it to an invalid variant. + +\o An object assigned to a QObject (or QObject-derived) list property will be +valid at the time of assignment. + +Following assignment, it is the responsibility of the class to subsequently guard +this pointer, either through a class specific method or the generic QPointer class. +\endlist + +Elements should assume that any QML assigned object can be deleted at any time, and +respond accordingly. If documented as such an element need not continue to work in +this situation, but it must not crash. + \section1 Signal Support \snippet examples/declarative/extending/signal/example.qml 0 |