[Qt-interest] QMetaObject::className() in constructors returns classname of baseclass

[Niklas Wulf]

Hi,

Thanks for pointing me to that. 
I thought of something like that.
And you're right, this really has not to be documented.

Niklas

Am 28.05.2010 um 19:50 schrieb Justin Noel:

> On 05/28/2010 01:36 PM, Niklas Wulf wrote:
>> Hi Qties,
>> 
>> I have some class Foo, which inherits QObject and QDomDocument, and some other classes Bar, which inherit Foo.
>> Calling metaObject()->className() in Foo's constructor returns "Foo" even it's a instance of Bar.
>> Am I wrong?
>> Is this wanted behavior?
>> Much more important: Shouldn't this be documented?
>> 
>> greetings Niklas
>> 
>> class Foo() : public QObject, public QDomDocument {
>> Q_OBJECT
>> public:
>> 	Foo(QObject* parent = 0) : QObject(parent), QDomDocument() { qDebug()<<  this->metaObject()->className(); }
>> 	void test() { qDebug()<<  this->metaObject()->className(); }
>> };
>> 
>> class Bar : public Foo {
>> Q_OBJECT
>> public:
>> 	Foo(QObject* parent = 0) : Foo(parent) {}
>> };
>> 
>> void main() {
>> 	Foo* bar = new Bar(/*some QObject**/); //prints "Foo"
>> 	bar.test(); //prints "Bar"
>> }
>>   
> 
> Effective C++ Tip #9: Never call virtual functions during construction or destruction
> http://www.artima.com/cppsource/nevercall.html
> 
> It's a c++ism and such doesn't need to be documented. Otherwise all virtual functions would need a warning. Check out this book for more good c++ practices: http://www.amazon.com/Effective-Specific-Improve-Programs-Designs/dp/0321334876/ref=sr_1_1?ie=UTF8&s=books&qid=1275068844&sr=8-1
> 
> Good Luck!
> --Justin
> 
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