CAObject

CAObject Detailed Description

Class Description

CAObject, root class of CrossApp engine, is mainly used to manage memory and define some call-back function pointers. The most classes of engine derive from it, and they all follow the same memory management mode.

Attribute

Access modifier	Attribute name	Description
Public	m_uID	The only id of object
Protected	m_uReference	Reference counter
Protected	m_uAutoReleaseCount	Auto release reference counter

Method

Access modifier	Method name	Description
Public	retain	Add object counter
Public	release	Minus object counter
Public	autorelease	Set auto management mode
Public	retainCount	Return current counter value of object
Public	isSingleReference	Instantiation object only has one user or not
Public	isEqual	Judge current object is same with appointed CAObject instantiation object or not

Attribute Intro

m_uID
Type: unsigned int
Description: It deploys accumulation mode and has a 0 initial value. Every time we create an object, m_u ID adds 1 as well as initialize current object’s m_uReference as 1 and m_uAutoReleaseCount as 0.

Example:

CAObject::CAObject(void): m_uReference(1) , m_uAutoReleaseCount(0)

{

    static unsigned int uObjectCount = 0;

    m_uID = ++uObjectCount;

}

m_uReference
Type: unsigned int
Description: reference counter, counter’s value is auto added 1 when each new object is created.

m_uAutoReleaseCount
Type: unsigned int
Description: auto manage object or not, if m_uAutoReleaseCount’s value is 0 then it deploys non-auto manage mode, when m_uAutoReleaseCount’s value is not 0 then it deploys auto manage mode.

Method Description

void retain(void)
Return value: void
Description: add 1 on m_uReference value of reference counter

Example:

void CAObject::retain(void)

{

    ++m_uReference;

}

void release(void)
Return value: void
Description: minus 1 on m_uReference value of reference counter, if m_uReference value is 0 then delete this object.

Example:

void CAObject::release(void)

{

    --m_uReference;

    if (m_uReference == 0)

    {

        delete this;

    }

}

CAObject autorelease(void)*
Return value: CAObject*
Description: set current object as auto memory management mode

Example:

CAObject* CAObject::autorelease(void)

{

    CCPoolManager::sharedPoolManager()->addObject(this);

    return this;

}

unsigned int retainCount(void) const
Return value: unsigned int
Description: return m_uReference value of current reference counter

Example:

unsigned int CAObject::retainCount(void) const

{

    return m_uReference;

}

bool isSingleReference(void) const
Return value: bool
Description: return if object only has one user or not via comparing to reference counter value

Example:

bool CAObject::isSingleReference(void) const

{

    return m_uReference == 1;

}

virtual bool isEqual(const CAObject pObject)*
Return value: bool
Description: virtual function, judge current object is same with instantiation object or not

Example:

bool CAObject::isEqual(const CAObject *pObject)

{

    return this == pObject;

}

CrossApp Memory Management Intro

CrossApp conducts memory management by adopting reference counter mode and all CAObject derived classes use this mode to manage object. The most basic rule is that the one who is in charge of new/retain also is responsible of release. When we create an object system will auto add a counter, and it will run a plus 1 operation on counter via retain method for every object citing; on the contrary, system will run a minus 1 operation on counter by calling release method for every object citing release. If reference counter’s m_uReference value is 0, then this object will be deleted.

Besides, CrossApp also provides another auto memory management method: when we are not sure about object’s release timing, we can call autorelease method to defer object release operation, at this moment object is in auto management status and is added to auto release pool. System will auto release all objects in pool to run a release operation after every time a frame is finished. If m_uReference value is 0, then current object will be deleted.