Use the pimpl idiom for all classes

[jakepetroules]

Each class should have exactly one member variable called 'd'. d shall be a pointer to a class named ClassNamePrivate. For example:

// HSSRenderer.h
class HSSRendererPrivate;
class HSSRenderer
{
public:
    HSSRenderer();
    ~HSSRenderer();
    int doSomething() const;

private:
    HSSRendererPrivate * const d; // const so we can't change what 'd' points to - this is desired in most cases
};

// HSSRenderer.cpp
class HSSRendererPrivate
{
public: // public to HSSRenderer, but private to everything else in practice since the class itself is only defined in the .cpp
    HSSRendererPrivate() : member1(), member2(), member3() // always use initializer lists
    int member1;
    int member2;
    int member3;
};

HSSRenderer::HSSRenderer() : d(new HSSRendererPrivate())
{
}

HSSRenderer::~HSSRenderer()
{
    delete d;
}

int HSSRenderer::doSomething() const
{
    // access to all of HSSRenderer's pseudo member variables is done through the d pointer
    return d->member1;
}

• Make sure that clone() methods copy the actual members of the *Private class; never just copy the pointer over
• Although AXR's convention is to always use this-> to reference class members, the d pointer itself should be an exception to this rule

http://en.wikipedia.org/wiki/Pimpl#C.2B.2B http://techbase.kde.org/Policies/Binary_Compatibility_Issues_With_C++#Using_a_d-Pointer http://qt-project.org/wiki/Dpointer http://zchydem.enume.net/2010/01/19/qt-howto-private-classes-and-d-pointers/