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QMetaType/Doc: update some wording about type registration

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Type registration isn't necessary any more, unless you're trying to look
up a name back to ID or QMetaType object. It hasn't been since 6.0.

Drive-by update the example not to use deprecated API.

Drive-by remove the paragraph about requirements that aren't accurate
any more.

Pick-to: 6.4
Task-number: QTBUG-104858
Change-Id: Ic6547f8247454b47baa8fffd170eecb66719fa65
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This commit is contained in:
Thiago Macieira 2022-08-26 11:53:00 -03:00
parent 30489eb661
commit 5ff637cc14
2 changed files with 18 additions and 21 deletions
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10
src/corelib/doc/snippets/code/src_corelib_kernel_qmetatype.cpp
View File

@ -35,12 +35,12 @@ MyStruct s2 = var.value<MyStruct>();
//! [3]
int id = QMetaType::type("MyClass");
if (id != QMetaType::UnknownType) {
void *myClassPtr = QMetaType::create(id);
QMetaType type = QMetaType::fromName("MyClass");
if (type.isValid()) {
void *myClassPtr = type.create();
...
QMetaType::destroy(id, myClassPtr);
myClassPtr = 0;
type.destroy(myClassPtr);
myClassPtr = nullptr;
}
//! [3]

29
src/corelib/kernel/qmetatype.cpp
View File

@ -417,7 +417,8 @@ const char *QtMetaTypePrivate::typedefNameForType(const QtPrivate::QMetaTypeInte
\omitvalue LastCoreType
\omitvalue LastGuiType
Additional types can be registered using Q_DECLARE_METATYPE().
Additional types can be registered using qRegisterMetaType() or by calling
registerType().
\sa type(), typeName()
*/
@ -465,17 +466,19 @@ const char *QtMetaTypePrivate::typedefNameForType(const QtPrivate::QMetaTypeInte
The class is used as a helper to marshall types in QVariant and
in queued signals and slots connections. It associates a type
name to a type so that it can be created and destructed
dynamically at run-time. Declare new types with Q_DECLARE_METATYPE()
to make them available to QVariant and other template-based functions.
Call qRegisterMetaType() to make types available to non-template based
functions, such as the queued signal and slot connections.
dynamically at run-time.
Any class or struct that has a public default
constructor, a public copy constructor, and a public destructor
can be registered.
Type names can be registered with QMetaType by using either
qRegisterMetaType() or registerType(). Registration is not required for
most operations; it's only required for operations that attempt to resolve
a type name in string form back to a QMetaType object or the type's ID.
Those include some old-style signal-slot connections using
QObject::connect(), reading user-types from \l QDataStream to \l QVariant,
or binding to other languages and IPC mechanisms, like QML, D-Bus,
JavaScript, etc.
The following code allocates and destructs an instance of
\c{MyClass}:
The following code allocates and destructs an instance of \c{MyClass} by
its name, which requires that \c{MyClass} have been previously registered:
\snippet code/src_corelib_kernel_qmetatype.cpp 3
@ -2775,9 +2778,6 @@ Q_CORE_EXPORT int qMetaTypeTypeInternal(const char *typeName)
Returns \c true if the object is saved successfully; otherwise
returns \c false.
The type must have been registered with Q_DECLARE_METATYPE()
beforehand.
Normally, you should not need to call this function directly.
Instead, use QVariant's \c operator<<(), which relies on save()
to stream custom types.
@ -2816,9 +2816,6 @@ bool QMetaType::save(QDataStream &stream, const void *data) const
Returns \c true if the object is loaded successfully; otherwise
returns \c false.
The type must have been registered with Q_DECLARE_METATYPE()
beforehand.
Normally, you should not need to call this function directly.
Instead, use QVariant's \c operator>>(), which relies on load()
to stream custom types.