SmartPtr

[Vincent Richomme]

I am trying to use Loki::SmartPtr and I
don't understand how it works :

I am using it like this :

// Gdiplus is a namespace holding objects used to draw on Windows
typedef Loki::SmartPtr<Gdiplus::GraphicsPath> GraphicsPathPtr ;

typedef std::vector<GraphicsPathPtr> GraphicsPathList;
typedef std::vector<GraphicsPathPtr>::iterator GraphicsPathListIt;

GraphicsPathPtr path;

LRESULT OnCreate(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
{
    AtlCreateEmptyMenuBar(m_hWnd);

    ...
    path = new GraphicsPath(FillMode::FillModeAlternate);

    return bHandled = FALSE;
}

LRESULT OnLButtonUp(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL&
bHandled)
{
    path.~SmartPtr();
    path = new GraphicsPath(FillMode::FillModeAlternate); // CRASH !!!!
    path->AddBeziers(&allPoints[0], allPoints.size());
    allPaths.push_back(&*path);
    allPoints.clear();

    return 0;
}

When my application is launched I create a Gdiplus::GraphicsPath, then user
draw on screen and
when he releases mouse button OnLButtonUp is called.

Inside OnLButtonUp  I first want to delete the pointer so path.~SmartPtr is called
that seem to delete the pointer.
However when I do path = new GraphicsPath(FillMode::FillModeAlternate); it
seems smart pointer
is still using the deallocated pointer and it crashs

I am sure I am doing something wrong but don't know what...

Regards

[Vincent Richomme]

path = NULL seems to work ...

[Rick van Haasen]

you shouldn't call the destructor,
just call
path = new GraphicsPath(FillMode::FillModeAlternate)

the smartpointer will do the householding: if it holds the only reference to the pointee, it will delete it before assigning it to the new object.

path = 0  causes the same effect, but extra step is not needed.

[Vincent Richomme]

Hum actually not sure it works fine ... because it still crash but later on.
I think smartpointer are too smart for me.

[Rick van Haasen]

before reassigning, you could check the reference count of the smrtptr, to see if the refcount is 1 . If not, another smartpointer (one that you store in the array?) still holds a reference to the object.