Does really property var mdl: model copies the full model object in memory?

[Kofr]

Hello guys,
I faced with this issue that I have to pass forward some data from one QML component to another and thus I created property var mdl: model when model here is quite heavy object.
Does QtQuick really copies this in memory or how does it works? and what is the difference with property alias?

[p3c0]

Hi @Kofr,
It is documented here. From the doc:

Property aliases are properties which hold a reference to another property. Unlike an ordinary property definition, which allocates a new, unique storage space for the property, a property alias connects the newly declared property (called the aliasing property) as a direct reference to an existing property (the aliased property).

So what I understand from it is that the first assignment (in your example) will copy into a new object while aliases holds the reference.

[Kofr]

@p3c0 so model in example is a model defined in C++ and instantiated in QML.
The question is
Does QML makes copy of this object (2 data models in memory) or it keeps only reference.
is it ducumented somewhere?

[A Former User]

@Kofr Hi! If you want to be really sure (because you don't trust the docs or your code ^_^) then add something like qDebug() << "hello"; to the destructor of the model and see how often that's called.