(for const functions use d_func() instead of Q_D) |
|||
| Line 8: | Line 8: | ||
public: | public: | ||
KFooBase(QObject *parent); | KFooBase(QObject *parent); | ||
| + | void setSomeInteger(int i); | ||
int someInteger() const; | int someInteger() const; | ||
protected: | protected: | ||
| Line 42: | Line 43: | ||
public: | public: | ||
KFooBase(QObject *parent); | KFooBase(QObject *parent); | ||
| + | void setSomeInteger(int i); | ||
int someInteger() const; | int someInteger() const; | ||
protected: | protected: | ||
| Line 55: | Line 57: | ||
public: | public: | ||
KFooDerived(QObject *parent); | KFooDerived(QObject *parent); | ||
| + | void setSomeInteger(int i); | ||
int sumOfIntegers() const; | int sumOfIntegers() const; | ||
protected: | protected: | ||
| Line 86: | Line 89: | ||
{ | { | ||
delete d_ptr; | delete d_ptr; | ||
| + | } | ||
| + | |||
| + | void KFooBase::setSomeInteger(int i) | ||
| + | { | ||
| + | Q_D(KFooBase); | ||
| + | d->someInteger = i; | ||
} | } | ||
int KFooBase::someInteger() const | int KFooBase::someInteger() const | ||
{ | { | ||
| − | + | // because of 'const' use d_func here instead of Q_D | |
| − | return | + | return d_func()->someInteger; |
} | } | ||
| Line 119: | Line 128: | ||
int KFooDerived::sumOfIntegers() const | int KFooDerived::sumOfIntegers() const | ||
{ | { | ||
| − | + | return d_func()->someInteger + d_func()->anotherInteger; | |
| − | + | ||
} | } | ||
</code> | </code> | ||
The following example illustrates the shared d-pointer concept. The class presented here derives from QObject to illustrate parameter-passing in the constructor; it is not necessary to be like that in your code.
class KFooBasePrivate;
class KFooBase : public QObject
{
public:
KFooBase(QObject *parent); void setSomeInteger(int i); int someInteger() const;
protected:
KFooBasePrivate * const d_ptr; KFooBase(KFooBasePrivate &dd, QObject *parent);
private:
KDE TechBase friend class KFooBasePrivate;
inline KFooBasePrivate *d_func() { return d_ptr; }
inline const KFooBasePrivate *d_func() const { return d_ptr; }
};
class KFooDerivedPrivate; class KFooDerived : public KFooBase { public:
KFooDerived(QObject *parent); int sumOfIntegers() const;
protected:
KFooDerived(KFooDerivedPrivate &dd, QObject *parent);
private:
friend class KFooDerivedPrivate;
inline KFooDerivedPrivate *d_func()
{ return reinterpret_cast<KFooDerivedPrivate *>(d_ptr); }
inline const KFooDerivedPrivate *d_func() const
{ return reinterpret_cast<KFooDerivedPrivate *>(d_ptr); }
};
class KFooBasePrivate;
class KFooBase : public QObject
{
public:
KFooBase(QObject *parent); void setSomeInteger(int i); int someInteger() const;
protected:
KFooBasePrivate * const d_ptr; KFooBase(KFooBasePrivate &dd, QObject *parent);
private:
Q_DECLARE_PRIVATE(KFooBase)
};
class KFooDerivedPrivate; class KFooDerived : public KFooBase { public:
KFooDerived(QObject *parent); void setSomeInteger(int i); int sumOfIntegers() const;
protected:
KFooDerived(KFooDerivedPrivate &dd, QObject *parent);
private:
Q_DECLARE_PRIVATE(KFooDerived)
};
/*** KFooBase ***/
class KFooBasePrivate
{
public:
virtual ~KFooBasePrivate() { }
int someInteger;
};
KFooBase::KFooBase(QObject *parent)
: QObject(parent), d_ptr(new KFooBasePrivate)
{ }
KFooBase::KFooBase(KFooBasePrivate &dd, QObject *parent)
: QObject(parent), d_ptr(&dd)
{ }
KFooBase::~KFooBase() {
delete d_ptr;
}
void KFooBase::setSomeInteger(int i) {
Q_D(KFooBase); d->someInteger = i;
}
int KFooBase::someInteger() const {
// because of 'const' use d_func here instead of Q_D return d_func()->someInteger;
}
/*** KFooDerived ***/
class KFooDerivedPrivate: public KFooBasePrivate { public:
int anotherInteger;
};
KFooDerived::KFooDerived(QObject *parent)
: KFooBase(*new KFooDerivedPrivate, parent)
{ }
KFooDerived::KFooDerived(KFooDerivedPrivate &dd, QObject *parent)
: KFooBase(dd, parent)
{ }
KFooDerived::~KFooDerived() {
/* no need to delete the d-pointer! */
}
int KFooDerived::sumOfIntegers() const {
return d_func()->someInteger + d_func()->anotherInteger;
}
