Cascades Development

[MedNez]

Hi all,

I downloaded some sample code:

https://github.com/blackberry/Presentations/tree/master/2012-BlackBerryJam-Americas/JAM09/BaDumTss

You will notice in the app.cpp and app.h files, the following lines in bold.

app.cpp

SoundPartyApp::SoundPartyApp()
{

   // create the qml etc.

   mSoundManager = new SoundManager("sounds/");
}

SoundPartyApp::~SoundPartyApp()
{
  // Destroy the sound manager.
  delete mSoundManager;
}

app.h

class SoundPartyApp: public QObject
{
Q_OBJECT

public:

  // This is our constructor to setup our badumtss2 application
  SoundPartyApp();

  // This is our destructor that frees the memory of the sound manager
  ~SoundPartyApp();
  // more stuff here etc

private:
  // The sound manager
  SoundManager *mSoundManager;
};

I understand this is with the old c++ code. The new app.hpp which I am using in beta 3, therefore, has a different "virtual" destructor:

class SoundPartyApp : public QObject
{
Q_OBJECT

public:

    SoundPartyApp(bb::cascades::Application *app);
    virtual ~SoundPartyApp() {}

    // etc

}

The new virtual ~SoundPartyApp() {} seems to conflict with the function in app.cpp.

Not sure why.

I have commented out the function and now it works... but I guess now I am not properly unallocating the soundmanager from memory. 

I can't seem to find any useful threads about how to get beta2 ~destructor functions working in beta3. 

Any Ideas?

[Dredvard]

I'm not sure what your error code is, but the virtual destructor should be different in beta 3 vs beta 2.  That's a c++ which affect things when they're cast.  Google the appropriate use of virtual destructors in cpp.

[MedNez]

Right, I've done some googling, and am I correct in suggesting that in Beta 2, you defined the destructor in the header file:

~SoundPartyApp();

 And then the function in the class file:

SoundPartyApp::~SoundPartyApp()
{
  // Destroy the sound manager.
  delete mSoundManager;
}

 But in Beta 3, the virtual destuctor already exists:

virtual ~SoundPartyApp() {}

So I should be able to just expand that, e.g.

virtual ~SoundPartyApp() {
    // do some important cleanup
    delete mSoundManager;
}

I got the idea from here:

http://stackoverflow.com/questions/461203/when-to-use-virtual-destructors 

(see the comment in the code ''// Do some important cleanup')

Looks like this is the place to do it? 

[Dredvard · Accepted solution]

If you want to relocate the code to the main app, just do this:

virtual ~SoundPartyApp();

And then in the main app do whatever you need to do:

 SoundPartyApp::~SoundPartyApp() {
    // do some important cleanup
    delete mSoundManager;
}

[MedNez]

Awesome. Worked perfectly, thanks!

Successfully updated some of the other Beta2 sample code now too - thank you.