Alias Cycle

Alias Property Is Part Of An Alias Cycle

What happened?

A property alias resolves to itself or to another alias resolving to itself.

Usually, a property alias should reference another property either directly, or indirectly by passing through another alias property.

If a property alias directly or indirectly references itself, then it forms an alias cycle. The warning indicates that the current alias property is inside or references an alias cycle, see 范例 .

Why is this bad?

Instances of components with alias cycles will not be created at runtime: they will be null instead.

范例

import QtQuick
Item {
    id: someId
    property alias myself: someId.myself // not ok: referring to itself
    property alias cycle: someId.cycle2 // not ok: indirectly referring to itself
    property alias cycle2: someId.cycle
    property alias indirect: someId.cycle // not ok: referring to alias indirectly referring to itself
}

You can fix this warning by breaking up the alias cycles:

import QtQuick
Item {
    id: someId
    Item {
        id: anotherId
        property string myself
        property int cycle
    }
    property alias myself: anotherId.myself // ok: referring to a property
    property alias cycle: someId.cycle2 // ok: does not refer to itself anymore
    property alias cycle2: anotherId.cycle // ok: not a cycle anymore
    property alias indirect: someId.cycle // ok: cycle does not form an alias cycle anymore
}