Question

QVariant (needed for QSettings class) supports creation from QMap<QString, QVariant>

But trying to initialise something like this:

QMap<QString, QVariant(QMap<QString, QVariant>)> i;

Gives the error:

function returning a function.

So then I tried the QMap<QString, QVariant> overload for QVariant() and got

error: no matching function for call to QVariant::QVariant(QMap<QString, QMap<QString, int> >&)

Now I tried a typecast:

QMap<QString, (QVariant)QMap<QString, QVariant> > i;

and got

template argument 2 is invalid
invalid type in declaration before ‘;‘ token

So what’s the required voodoo to convert a nested QMap to a QVariant object?

Answer 1

The error being reported is that QVariant(...) is not a type, but a function (c-tor).

You should have just used: Map<QString, QVariant> i; and used QVariant(QMap<QString, QVariant>) only when assigning values to the map. The point is QVariant is anything really. So a map of QVariants, can have an int in one position (contained in the QVariant) and a QDate in another. So when declaring the type, you can’t specify which types you want QVariant to hold.