Ah you mean by "knowing types at compile time" is actually defined types, so you actually defining classes at run-time?
2016-03-02 13:04 GMT+02:00 Nye <kshegu...@gmail.com>: > I just meant that in my case the classes are defined in the user > application, so the library has no notion whatsoever what classes it has > available to create instances from and it depends on the meta-type system > exclusively for that (while still handling the > serialization/deserialization of said instances). It just makes a factory > inapplicable in my case (at least if you're not counting the meta-type > system as a factory). > > > On Wed, Mar 2, 2016 at 12:58 PM, André Somers <an...@familiesomers.nl> > wrote: > >> >> >> Op 02/03/2016 om 11:51 schreef Sina Dogru: >> >> > For now there is a design choice which I feel weak myself, to do >>> factory or to use QMetaType for creating instances. >>> >>> Depends on the use case I suppose. If you know the types at compile >>> time, as is usually the case I'd go with the simple solution to make a >>> factory. I recently, however, had a case where the deserialization routine >>> couldn't know at compile time the exact type (i.e. for a library), so I had >>> to put a (gadget) base class and use the runtime type ids. >>> >> >> Since I'm trying to recover states of the QObject-derived class instances >> from a file, it is not possible to know the types at compile time. But is >> not that factory was also for creating objects that type is known at >> run-time? Or am I missing something? Because I thought both factory and >> metaobject system provide run-time object creation? >> >> You are right. If you know the type you need at compile time, just >> construct the instance directly. >> Factories are useful for the creation of objects who's types you do _not_ >> know at compile time. And indeed, as demonstrated above, the metaobject >> system together with the metatype system can also be abused to do the same >> thing. >> >> André >> >> >
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