[PyQt] signal

[Phil Thompson]

On Fri, 11 Feb 2011 15:31:09 +0100, John Beuving <johnbeuving at gmail.com>
wrote:
>>
>> Hi,
>>
>> I have the following error when running my C++ code from python.
>> The C++ code is a multiple inheritance class. It is a worker thread 
>> which has to emit events.
>> Why doesn't this work ?
>>
>> File "test.py", line 165, in __init__
>>     self.didSomething.connect(self.handletrigger)
>> TypeError: pyqtSignal must be bound to a QObject, not 'ImageWriter'
>>
>> C++ header file:
>>
>>         class QtWorker: public QObject, public Worker {
>>         public:
>>             QtWorker(const std::string& name=""): Worker(name), 
>> p_widget(0) {}
>>             virtual ~QtWorker() {}
>>
>>             QWidget* GetWidget() {return p_widget;}
>>
>>         protected:
>>             QWidget* p_widget;
>>         };
>>
>>
>> SIP Code:
>>
>> namespace core
>> {
>>     class QtWorker: QObject, core::Worker
>>     {
>> %TypeHeaderCode
>> #include "core/Qtworker.h"
>> %End
>>         public:
>>             QtWorker(const string& name);
>>
>>             void *GetWidget();
>>
>>     };
>> };
>>
>> Python Code:
>>
>> class ImageWriter(core.QtWorker):
>>
>>     didSomething = pyqtSignal()
>>
>>     def __init__(self):
>>         super(ImageWriter,self).__init__()
>>         self.didSomething.connect(self.handletrigger)
>>
>>     def Process(self):
>>         self.didSomething.emit()
>>         return True
>>
>>     def handletrigger(self):
>>         print "ImageWriter signal received"
>>
> I tried to investigate the problem I had further. The problem is that 
> there is no way to cast the QtWorker to a QObject.
> The reason for this is that in the list of supers for the QtWorker 
> object there is no 'correct' reference to QObject.
> When comparing the list of types in the generated code of QtCore and the

> list of supertypes in my generated there seems to be a problem.
> To be more precise:
> 
> In the generated cpp code of QtWorker
> 
> /* Define this type's super-types. */
> static sipEncodedTypeDef supers_core_QtWorker[] = {{96, 0, 0}, {26, 255,

> 1}};
> 
> This means that there are 2 supers, One from the own module typenumber 
> 26, as found in the header file:
> 
> #define sipType_core_Worker              sipModuleAPI_PyMPT.em_types[26]
> 
> And the first one from another module (index 0) index 96
> 
> #define sipType_QList_0101QAbstractTransition      
> sipModuleAPI_QtCore.em_types[96]
> 
> Which is obviously not the QObject I'm looking for. In the init procudre

> of my module I can also see that a superclass type is register from 
> QList::QAbstractTransition
> But this clearly is very wrong.
> The number 96 can be found in my own code correctly:
> 
> #define sipType_QObject              
> sipModuleAPI_PyDySI_QtCore->em_types[96]
> 
> However this type is created after the QtWorker
> 
> My question is, where does sip get these numbers, and how can I fix
this.

The numbers are assigned when SIP parses the %Imported Qt .sip files. This
relies on those files being parsed in the same way as when PyQt was built.

The most likely cause of the problem is that you are passing different
flags to SIP than those used to build PyQt. The only safe way to get this
right is to get the information from the pyqtconfig module, specifically
the pyqt_sip_flags configuration attribute.

Phil