Why are upper-cased properties not supported in QML?

[mwallnoefer]

What is the reason that Qt properties need to begin with a lower-cased letter in order to be exposed to QML?

Example: this works

C++

class Model : public QAbstractListModel
{
...
    Q_PROPERTY(int name READ name WRITE setName NOTIFY nameChanged)
    Q_PROPERTY(int age READ age WRITE setAge NOTIFY ageChanged)
...
};

QML:

Person {
   name: "Otto"
   age: 30
...
}

This not (odd error message in the QML code at runtime):

class Model : public QAbstractListModel
{
...
    Q_PROPERTY(int Name READ name WRITE setName NOTIFY nameChanged)
    Q_PROPERTY(int Age READ age WRITE setAge NOTIFY ageChanged)
...
};

QML:

Person {
   Name: "Otto"
   Age: 30
...
}

[raven-worx]

@mwallnoefer
because there are default created changed-slots for each property following the pattern on<CamelCasePropertyName>Changed() (if NOTIFY was specified)

[mwallnoefer]

Okay, but it seems that also the following piece does not work or am I missing something? Also when omitting the NOTIFY clause I get always the same "Invalid attached object assignment" error.

class Model : public QAbstractListModel
{
...
    Q_PROPERTY(int Name READ Name WRITE setName NOTIFY NameChanged)
    Q_PROPERTY(int Age READ Age WRITE setAge NOTIFY AgeChanged)
...
};

For me this seems more like a bug, since in C++ code upper cased properties are perfectly valid. Alternatively, the docs could be updated to contain an explicit reference to this restriction of QML (for instance in the section about Q_PROPERTY):

[Julien B]

Hello @mwallnoefer,

The documentation currently refers to this in property attributes

[mwallnoefer]

@Julien-B Okay, but then it should go also in the Q_PROPERTY section.

But the interesting thing is, that person.Name or person.Age does work though. Only the class assignment syntax with the colon does not.

[Thomas Hartmann]

Capital letter properties are reserved for so called attached properties (http://doc.qt.io/qt-5/qtqml-syntax-objectattributes.html).