Greetings,
during last years of development with QML I always wondered how to solve
certain software engineering problems.
First, defining private properties: I have seen sometimes doing:
Item {
property int publicProp: 40 + state.privateProp
QtObject {
id: state
property int privateProp: 2
}
}
which seems a rather clever workaround, except for some reason it does not
work with QtObject itself (error: Cannot assign to non-existent default
property):
QtObject {
property int publicProp: 40 + state.privateProp
QtObject {
id: state
property int privateProp: 2
}
}
it is possible to do:
QtObject {
property int publicProp: 40 + _.privateProp
property QtObject _: QtObject {
property int privateProp: 2
}
}
but it exposes the private QtObject so it kind of defeats its purpose.
Then, another rather important thing is the overriding (of properties and
methods) in derived components, e.g.:
//BaseObject.qml
Item {
readonly property bool canFly: false
function foo() { console.log('foo()') }
}
//ExtendedObject.qml
BaseObject {
canFly: true // Invalid property assignment: "canFly" is a read-only
property
function foo() { console.log('foo() overridden') }
}
the property-overriding pattern would work only if the property is
writable, which is not intended.
the method-overriding pattern doesn't give any error and seems to work also
when casting an instance x of ExtendedObject with 'as', e.g.: (x as
BaseObject).foo() so I wonder if this is legal and it would be the
preferred way for overriding things (behavior) in derived components.
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