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Functor as event engine

By , 8 Mar 2005
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Functor implementation

Functor is a wrapper around function. It's useful to unify static and member function calls. Also it's profitable for event mechanism creation.

Syntax represented below works only on MSVC++ 7.1, this file have defines for 6.0 also but you won't be happy using them.


IFunctor - common interface for all functors. It has few functions:

Call() - calls bounded function,

operator () - calls Call

IsEqual(IFunctor *) - returns true if both functors are bounded with the same function.


IFunctor is inherited from IRefCounted

IRefCounted has these methods:

AddRef() - increments reference counter

Release() - decrements reference counter and deletes object when reference count is zero.

DecreaseRef() - decrements reference counter without deletion

GetFunctor() - overloaded function that creates functor, returns IFunctor

GetFunctor(StaticFunction) - creates static functor

GetFunctor(&obj/*CMyObj */, CMyObj::Function) - creates member functor

GetFunctor(pFunctor/*IFunctor* */) - creates member functor


GetFunctor returns pointer to IFunctor with zero reference counter. So AddRef and then Release will free allocated memory.

CFunctorSet - container for IFunctor*. Also derived from IFunctor, has methods:

operator +=(IFunctor*) - appends functor

operator -=(IFunctor*) - removes functor (and not only if pointers are equal: it uses IsEqual on functors)

Call - calls all functors

operator () -calls Call


operator +=() calls AddRef on given functor pointer

operator -=() calls Release on given functor pointer

So though GetFunctor allocates memory, CFunctorSet releases it.

Thus, in different cases  you must first AddRef and then after all Release pointer returned by GetFunctor.


            CFunctorSet<void (*)(int)> m_vMyEvent;

            void MyStaticFn(int){}

            class CMyClass{
                void MyMemFn(int){}

            CMyClass obj;
            m_vMyEvent+=GetFunctor(&obj, CMyClass::MyMemFn);
            m_vMyEvent(1); //calls both functions
            m_vMyEvent-=GetFunctor(MyStaticFn); //it works 'cause operator -=() uses IsEqual
            m_vMyEvent(2); //calls only member function of CMyClass obj.


CDeferredFunctor - intended for deferred calls in cross thread communication. Methods:

constructor - binds functor

operator =() - binds functor

Call - stores arguments

DeferredCall - calls bounded functor with stored arguments

IsCalled() - returns true if Call is already made but DeferredCall is still not

DeferredCallSaveResult() - saves result of calling

GetResult() - returns result saved by DeferredCallSaveResult

SetOnCall() - allows to set functor that will be called during Call

CRemoteFunctor - same as CDeferredFunctor but stores arguments in IStream. Methods:

constructor - binds functor

Call - stores arguments

RemoteCall - calls bounded functor with stored arguments

GetData(IStream * pStream) - copies internal stream to given

SetData(IStream * pStream, bool bRewind=true) - copies given stream to the internal, sets given stream to start optionally before copying

SetOnCall - allows to set functor that will be called during Call


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About the Author

Software Developer (Senior)
Russian Federation Russian Federation
Real christian since 1997 (to be a cristian means to follow Jesus Christ)
Programmer since 1999
main language is C++ and I fond of it!
Married to beautiful and clever sister in Christ since 2001
Musician lead guitar - since 1995, vocal since 2004. I play neoclassic-doom-progressive-death metall.

Comments and Discussions

Generalnew comments Pinmemberaraud9-Mar-05 22:19 
GeneralBad programming PinmemberChristian Graus8-Mar-05 14:58 
GeneralRe: Bad programming Pinmemberaraud8-Mar-05 17:45 
GeneralRe: Bad programming PinmemberChristian Graus8-Mar-05 17:55 
GeneralRe: Bad programming Pinmemberaraud8-Mar-05 19:38 
GeneralHmmmm PinmemberKochise8-Mar-05 21:42 
GeneralRe: Hmmmm Pinmemberaraud8-Mar-05 23:28 
GeneralI don't believe in God... PinmemberKochise9-Mar-05 0:27 
GeneralRe: I don't believe in God... Pinmemberaraud9-Mar-05 1:08 
GeneralHey :) PinmemberKochise9-Mar-05 1:53 

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