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

[Schimkowitsch Robert]

To - partially - answer my own question:
 
Whether QMetaType::type fails or succeeds is not related to my type
string.
It works after I have called the following line of code:
int id = qMetaTypeId<CCmn_UIUpdateTimer*>();
 
If I put that line first, both calls to QMetaType::type succeed
I would greatly appreciate if someone could explain why that is so, or
if there are other ways to ensure QMetaType::type succeeds.
 
Kind regards

Robert Schimkowitsch 
Automation
Development Control Center Systems 
ANDRITZ HYDRO GmbH
EURO PLAZA - Building D
Wienerbergstrase 41
1120 Vienna, Austria 
Phone (+43/1) 81195-6767
Fax (+43/1) 81195-6954
e-mail: robert.schimkowitsch at andritz.com 
Internet: www.andritz-hydro.com 

 

________________________________

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 Schimkowitsch Robert
Sent: Monday, September 26, 2011 4:15 PM
To: qt-interest at qt.nokia.com
Subject: *Spoofed Mail* [Qt-interest] QMetaType::type succeeds or fails
seemingly randomly



I generate a type name using two different ways, and come up with the
exact same string both times 
(that is, I did a .toAscii for both, then compared each character in a
byte array, and they all come up equal). 

Still, for one of the source strings, the resulting MetaType id is
valid, for the other string it is zero. 

Here's my test code: 

// First, write a user-defined enum to a QVariant 
// The enum is defined in a Q_OBJECT-Class, and has Q_ENUMS and
Q_DECLARE_METATYPE applied to it 
    CCmn_UIUpdateTimer::EUiActivityMode resultMode =
vActivityMode.value<CCmn_UIUpdateTimer::EUiActivityMode>(); 

// Assume we just get the QVariant, without knowing anything about the
enum 
// Let's see how much we can find out using the MetaObject system 
    QString enumTypeName = vActivityMode.typeName(); 
    QString enumParentTypeName = enumTypeName.section("::",0,0); 
// Assume the enum's parent class is registered with "ClassName"* 
    enumParentTypeName.append("*"); 
// Try to get the type id of the parent class, so I can get QMetaEnum
information 
    int enumParentTypeId =
QMetaType::type(enumParentTypeName.toAscii()); 


// Comparison: Let's get the meta information directly from the enum's
parent object 
    const QMetaObject& metaObject =
CCmn_UIUpdateTimer::staticMetaObject; 
    int id = qMetaTypeId<CCmn_UIUpdateTimer*>(); 
    QString realClassType = QMetaType::typeName(id); 
    int realId = QMetaType::type(realClassType.toAscii()); 

// Now output the results 
    qDebug() << "Type name from qMetaTypeId" << realClassType 
             << "Type id determined from realClassName"  << realId 
             << "Type name determined from enum type name" <<
enumParentTypeName 
             << "Type id determined from enumParentTypeName" <<
enumParentTypeId 
             << "Type name comparison result" 
             << realClassType.compare(enumParentTypeName); 

The output looks like this: 

Type name from qMetaTypeId "CCmn_UIUpdateTimer*" 
Type id determined from realClassName 259 
Type name determined from enum type name "CCmn_UIUpdateTimer*" 
Type id determined from enumParentTypeName 0 
Type name comparison result 0 

I have two identical strings. I use them both in QMetaType::type 
Why does one return a type id, the other not? 

Kind regards 

Robert Schimkowitsch 

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Thank You. 

________________________________

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Thank You.
  ANDRITZ HYDRO GmbH
  Rechtsform/ Legal form: Gesellschaft mit beschrankter Haftung / Corporation 
  Firmensitz/ Registered seat: Wien 
  Firmenbuchgericht/ Court of registry: Handelsgericht Wien 
  Firmenbuchnummer/ Company registration: FN 61833 g
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  UID-Nr.: ATU14756806
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