[Qt-interest] QMetaType::type succeeds or fails seemingly

[Schimkowitsch Robert]

I don't store the object, I read it's properties, which are mostly
primitive types (int, double), standard Qt types (QString, QColor) or
custom-defined enums.

I don't have to know the type of a QObject to be able to read it's
properties. But I rely that the metatypes it defines (e.g. enums) are
already registered, otherwise it won't work.

Kind regards

Robert Schimkowitsch


-----Original Message-----
From: qt-interest-bounces+robert.schimkowitsch=andritz.com at qt.nokia.com
[mailto:qt-interest-bounces+robert.schimkowitsch=andritz.com at qt.nokia.co
m] On Behalf Of Stephen Kelly
Sent: Friday, September 30, 2011 12:11 PM
To: qt-interest at qt.nokia.com
Subject: Re: [Qt-interest] QMetaType::type succeeds or fails seemingly

Schimkowitsch Robert wrote:

> I can't use qRegisterMetaType<MyType>(), because I don't know the type
> at compile time.

If MyType is-a QObject, then you should store it as a QObject in the 
QVariant, don't store it as MyType and don't even use 
QDECLARE_METATYPE(MyType*).




> The type is defined inside a library, and I only get it by iterating
> through the properties of a QObject-based class defined within that
> library.
> 
> My test code knew the type, but that was just test code.
> In my real app, I try to set the properties of an unknown
QObject-based
> class from an input XML file.
> I iterate through all properties. If they are an enumeration type, I
get
> the QMetaEnum information. If the string from the XML file matches any
> of the enum keys, I assign the enum that value.
> 
> What would really help me would be some method I could call on the
> QObject that would ensure all DECLARE_METATYPE enums related to that
> object are resolved.
> 
> Kind Regards
> 
> Robert Schimkowitsch
> 
> -----Original Message-----
> From:
qt-interest-bounces+robert.schimkowitsch=andritz.com at qt.nokia.com
>
[mailto:qt-interest-bounces+robert.schimkowitsch=andritz.com at qt.nokia.co
> m] On Behalf Of Thiago Macieira
> Sent: Wednesday, September 28, 2011 10:31 AM
> To: qt-interest at qt.nokia.com
> Subject: Re: [Qt-interest] QMetaType::type succeeds or fails seemingly
> 
> On Wednesday, 28 de September de 2011 10:15:34 Stefan Majewsky wrote:
>> On Mon, Sep 26, 2011 at 4:50 PM, Schimkowitsch Robert
>> 
>> <Robert.Schimkowitsch at andritz.com> wrote:
>> > Which brings up the question: When does Q_DECLARE_METATYPE run, and
> how
>> > do I make it run?
>> 
>> Looking at the definition of Q_DECLARE_METATYPE, in
>> include/QtCore/qmetatype.h, you should be able to "make it run" by
>> 
>>     (void) QMetaType<MyType>::qt_metatype_id();
>> 
>> before the QMetaType::type() call. I don't know about the ABI
>> stability policy for this macro, but I think this should be
>> binary-compatible until at least Qt 5.
> 
> You can use the documented way:
> qRegisterMetaType<MyType>();
> 


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