This class is just a typedef to wxRefCounter and is used by wxObject.
- Derive classes from this to store your own data. When retrieving information
- from a wxObject's reference data, you will need to cast to your own derived class.
+ Derive classes from this to store your own data in wxObject-derived
+ classes. When retrieving information from a wxObject's reference data,
+ you will need to cast to your own derived class.
+
+ Below is an example illustrating how to store reference counted
+ data in a class derived from wxObject including copy-on-write
+ semantics.
@section objectrefdata_example Example
m_refData = new MyCarRefData();
M_CARDATA->m_price = price;
}
-
+
wxObjectRefData *MyCar::CreateRefData() const
{
return new MyCarRefData;
{
if (m_refData == car.m_refData)
return true;
- if (!m_refData || !car.m_refData)
+ if (!m_refData || !car.m_refData)
return false;
// here we use the MyCarRefData::operator==() function.
}
@endcode
-
+
@library{wxbase}
@category{rtti}
/**
@class wxRefCounter
- This class is used to manage reference-counting.
+ This class is used to manage reference-counting providing a simple
+ interface and a counter. wxRefCounter can be easily used together
+ with wxObjectDataPtr<T> to ensure that no calls to wxRefCounter::DecRef()
+ are missed - thus avoiding memory leaks.
+
+ wxObjectRefData is a typedef to wxRefCounter and is used as the
+ built-in reference counted storage for wxObject-derived classes.
@library{wxbase}
@category{rtti}
@library{wxbase}
@category{rtti}
- @see wxClassInfo, @ref overview_debugging, @ref overview_refcount,
+ @see wxClassInfo, @ref overview_debugging, @ref overview_refcount,
wxObjectDataRef, wxObjectDataPtr<T>
*/
class wxObject
Ensure that this object's data is not shared with any other object.
If we have no data, it is created using CreateRefData();
- if we have shared data (i.e. data with a reference count greater than 1),
+ if we have shared data (i.e. data with a reference count greater than 1),
it is copied using CloneRefData(); otherwise nothing is done (the data
is already present and is not shared by other object instances).
-
+
If you use this function you should make sure that you override the
CreateRefData() and CloneRefData() functions in your class otherwise
an assertion will fail at runtime.
/**
Creates a new instance of the wxObjectRefData-derived class specific to
this object and returns it.
-
+
This is usually implemented as a one-line call:
@code
wxObjectRefData *MyObject::CreateRefData() const
/**
Creates a new instance of the wxObjectRefData-derived class specific to
this object and initializes it copying @a data.
-
+
This is usually implemented as a one-line call:
@code
wxObjectRefData *MyObject::CloneRefData(const wxObjectRefData *data) const
/**
- This is an helper template class primarily written to avoid memory leaks because of
- missing calls to wxObjectRefData::DecRef().
+ This is an helper template class primarily written to avoid memory leaks because
+ of missing calls to wxRefCounter::DecRef() and wxObjectRefData::DecRef().
Despite the name this template can actually be used as a smart pointer for any
class implementing the reference counting interface which only consists of the two
counting to be in the class pointed to, where instead wxSharedPtr<T> implements the
reference counting itself.
+ Below is an example illustrating how to implement reference counted
+ data using wxRefCounter and wxObjectDataPtr<T> with copy-on-write
+ semantics.
+
@section objectdataptr_example Example
@code
- class MyCarRefData: public wxObjectRefData
+ class MyCarRefData: public wxRefCounter
{
public:
- MyCarRefData() { m_price = 0; }
-
- MyCarRefData( const MyCarRefData& data )
- : wxObjectRefData()
- {
- m_price = data.m_price;
- }
+ MyCarRefData( int price = 0 ) : m_price(price) { }
+ MyCarRefData( const MyCarRefData& data ) : m_price(data.m_price) { }
void SetPrice( int price ) { m_price = price; }
int GetPrice() const { return m_price; }
- bool operator == ( const MyCarRefData& other ) const
- {
- return m_price == other.m_price;
- }
-
protected:
int m_price;
};
public:
// initializes this MyCar assigning to the
// internal data pointer a new instance of MyCarRefData
- MyCar( int price ) : m_data( new MyCarRefData )
+ MyCar( int price = 0 ) : m_data( new MyCarRefData(price) )
{
- m_data->SetPrice( price );
}
MyCar& operator =( const MyCar& tocopy )
if (m_data.get() == other.m_data.get())
return true; // this instance and the 'other' one share the
// same MyCarRefData data...
-
- // rely on the MyCarRefData::operator==()
- return (*m_data.get()) == (*other.m_data.get());
+
+ return (m_data.GetPrice() == other.m_data.GetPrice());
}
void SetPrice( int price )
// make sure changes to this class do not affect other instances
// currently sharing our same refcounted data:
UnShare();
-
+
m_data->SetPrice( price );
}
projects / wxWidgets.git / blobdiff