Class inheriting QQbject

[Nicu Tofan]

Hello!

I need a class in python that can be created on some circumstances:

inst = example.Foo()
inst.someMethod()

and, on other circumstances, I want it to be created for the user prior to first line of the custom script:

# inst2 is already part of this module
inst2.someMethod()

The way I understand the examples, this means that:
- for first use case I need a wrapper:

class _w_Foo : public QObject{
Q_OBJECT
public slots:
  void someMethod(Foo * o) { o->someMethod(); }
}

- for second use case I need my class to inherit QObject:

class Foo : public QObject{
Q_OBJECT
public slots:
  void someMethod() { /* do somthing */; }
}

Is there any other way?

PS there may be syntactic errors in code up there, I didn't checked it. Just extract the idea. :)

[Chris Bevan]

Hi Nick,

The way I do this is using PythonQt's decorators.  Here's a rough example from some code:

class Test : public QObject
{
    Q_OBJECT
public slots:
    void run();
};
class TestDecorator : public QObject
{
    Q_OBJECT
public slots:
    Test* new_Test();
};

Provided that you register the decorators and then the class before you use either of them, this should let you do any of the following:

test1 = my_module.getSomeTest()
test1.run()
test2 = my_module.Test()    # you'll need to copy this from PythonQt.private
test2.run()

Hope that helps.

- Chris

[Nicu Tofan]

Thank you for your help, Chris! There is something that I'm missing here. A little example may help.

This is how I define the classes that you have used (minimal changes):

class Test : public QObject {
    Q_OBJECT
public slots:
    QString run()
    { return "run slot called!"; }
};
class TestDecorator : public QObject {
    Q_OBJECT
public slots:
    Test* new_Test()
    { return new Test(); }
};

Now here is the code that makes use of these classes. There are comments indicating the output and the missing routine:

void    test__newmodule                 ( void )
{
    PythonQt * sgl = PythonQt::self();
    PythonQtObjectPtr module = sgl->createUniqueModule();
    sgl->addDecorators( new TestDecorator() );
    sgl->registerCPPClass( "Test", "", "example" );
    module.evalScript( "print( dir() )\n");
    //OUTPUT: ['__builtins__', '__doc__', '__file__', '__name__', '__package__']
    module.evalScript( "from PythonQt import example\n");
    module.evalScript( "print( dir() )\n");
    //OUTPUT: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'example']
    module.evalScript( "print( dir( example ) )\n");
    //OUTPUT: ['Test', '__doc__', '__name__', '__package__']
    module.evalScript( "print( dir( example.Test ) )\n");
    //OUTPUT: ['__dict__', '__doc__', '__module__', '__weakref__', 'className', 'delete', 'help', 'inherits']
    /* I would have expected to see run here */
    module.evalScript( "tinst = example.Test()\n");
    module.evalScript( "print( dir() )\n");
    //OUTPUT: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'example', 'tinst']
    module.evalScript( "print( dir( tinst ) )\n");
    //OUTPUT: ['__dict__', '__doc__', '__init__', '__module__', '__weakref__', 'className', 'delete', 'help', 'inherits']
    /* I would have expected to see run here */
    PythonQtObjectPtr module2 = sgl->createUniqueModule();
    module2.addObject( "predef_inst", new Test() );
    module2.evalScript( "print( dir() )\n");
    //OUTPUT: ['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'predef_inst']
    module2.evalScript( "print( dir( predef_inst ) )\n");
    //OUTPUT: ['__dict__', '__doc__', '__init__', '__module__', '__weakref__', 'className', 'delete', 'help', 'inherits']
    /* I would have expected to see run here */

}

[Chris Bevan]

Hmmm…  You're doing things pretty similarly to my code there, and I would have expected those dir commands to show "run" as you say.  The only significant difference I've spotted is that you're calling PythonQt::registerCPPClass(), whereas I'm calling PythonQt::registerClass().  That might make a difference, given that PythonQt wraps QObject classes and general C++ classes in different ways.  Does changing that help at all?

- Chris

[Nicu Tofan]

that's right, that was the problem. Thank you, Chris!

For future reference, the line

sgl->registerCPPClass( "Test", "", "example" );

should be replaced with this one:

sgl->registerClass( &Test::staticMetaObject, "example" );

Nick