[Qt-interest] Q_DECLARE_METATYPE and abstract classes

[Thiago Macieira]

On Monday, 8 de August de 2011 12:36:16 Schimkowitsch Robert wrote:
> > How do I declare a metatype of an abstract base class? I have seen
> > nothing in the Q_DECLARE_METATYPE-docs that would forbid it.

You don't. Metatypes require being default-constructible, publicly 
destructible, copyable and assignable.

Abstract types cannot be constructed at all. By definition of abstract as well, 
you don't want to copy them, as doing that would shear the specialised object 
you had.

More than likely, you want to register the metatype of the *pointer* to the 
abstract class.

> > I need the metatype to create a Q_PROPERTY of (a pointer to) that
> > abstract type. The compiler errors are clear enough: It wants to
> > create a new object of that type, which doesn't work with an abstract
> > class.

See? That proves all I said above: you cannot have a metatype of an abstract 
type and you want the pointer to the type.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
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