path: root/src/corelib/kernel/qmetaobject.cpp
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authorGiuseppe D'Angelo <>2020-01-03 17:18:02 +0100
committerGiuseppe D'Angelo <>2020-10-03 11:47:17 +0200
commit889d40ebe2d9d0e92caea2749608720f7c088173 (patch)
treea68214fbf5a0dc9b1488e4ae79a499dabc1cc445 /src/corelib/kernel/qmetaobject.cpp
parent990e2e4fb8ef546b89b5e83e659771edd5b4ed3e (diff)
Centralize the implementation of move assignment operators
At the moment we have two main strategies for dealing with move assignment in Qt: 1) move-and-swap, used by "containers" (in the broad sense): containers, but also smart pointers and similar classes that can hold user-defined types; 2) pure swap, used by containers that hold only memory (e.g. QString, QByteArray, ...) as well as most implicitly shared datatypes. Given the fact that a move assignment operator's code is just boilerplate (whether it's move-and-swap or pure swap), provide two _strictly internal_ macros to help write them, and apply the macros across corelib and gui, porting away from the hand-rolled implementations. The rule of thumb when porting to the new macros is: * Try to stick to the existing code behavior, unless broken * if changing, then follow this checklist: * if the class does not have a move constructor => pure swap (but consider ADDING a move constructor, if possible!) * if the class does have a move constructor, try to follow the criteria above, namely: * if the class holds only memory, pure swap; * if the class may hold anything else but memory (file handles, etc.), then move and swap. Noteworthy details: * some operators planned to be removed in Qt 6 were not ported; * as drive-by, some move constructors were simplified to be using qExchange(); others were outright broken and got fixed; * some contained some more interesting code and were not touched. Change-Id: Idaab3489247dcbabb6df3fa1e5286b69e1d372e9 Reviewed-by: Allan Sandfeld Jensen <>
Diffstat (limited to 'src/corelib/kernel/qmetaobject.cpp')
1 files changed, 8 insertions, 0 deletions
diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index c537293347..3bb3e33465 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -1598,6 +1598,14 @@ bool QMetaObject::invokeMethodImpl(QObject *object, QtPrivate::QSlotObjectBase *
+ \fn QMetaObject::Connection::swap(Connection &other)
+ \since 5.15
+ Swaps this Connection instance with \a other. This operation is very fast
+ and never fails.
\class QMetaMethod
\inmodule QtCore