Add a convenient way to get a type-erased smart pointer from a QVariant.

Any known smart pointer in a QVariant can be handled in this way. The
metatype system can be informed of new smart pointer types using an
existing macro which is now documented.

This is very similar to the existing infrastructure
for containers.

Change-Id: Iac4f9fabbc5a0626c04e1185d51d720b8b54603d
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/src/corelib/doc/snippets/code/src_corelib_kernel_qmetatype.cpp b/src/corelib/doc/snippets/code/src_corelib_kernel_qmetatype.cpp
index cb1346f74c..0af10af36d 100644
--- a/src/corelib/doc/snippets/code/src_corelib_kernel_qmetatype.cpp
+++ b/src/corelib/doc/snippets/code/src_corelib_kernel_qmetatype.cpp
@@ -143,3 +143,31 @@ void someFunc()
 
 //! [11]
 
+//! [12]
+QPointer<QFile> fp(new QFile);
+QVariant var = QVariant::fromValue(fp);
+// ...
+if (var.canConvert<QObject*>()) {
+    QObject *sp = var.value<QObject*>();
+    qDebug() << sp->metaObject()->className(); // Prints 'QFile'.
+}
+//! [12]
+
+//! [13]
+
+#include <memory>
+
+Q_DECLARE_SMART_POINTER_METATYPE(std::shared_ptr)
+
+void someFunc()
+{
+    auto smart_ptr = std::make_shared<QFile>();
+    QVariant var = QVariant::fromValue(smart_ptr);
+    // ...
+    if (var.canConvert<QObject*>()) {
+        QObject *sp = var.value<QObject*>();
+        qDebug() << sp->metaObject()->className(); // Prints 'QFile'.
+    }
+}
+
+//! [13]