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Using const references as local smart pointer?

I am fine-tuning some last minute things in my c++ allocator lib and was
thinking of ways to manage local references to system objects created with
factory functions. I started to tinker around with using const references to
represent a smart-pointer template that uses intrusive reference counting.
Anyway, here is a short little program that should clearly demonstrate what
I am messing around with:

_______________ __________
#include <cstdio>
#include <exception>
template<typena me T>
class AutoRef {
mutable T *m_State;

public:
AutoRef(T* const State) throw() : m_State(State) {
printf("(%p)Aut oRef::AutoRef(% p)\n", (void*)this, (void*)State);
}

~AutoRef() throw() {
T::RefCount_XAd d(m_State, -1);
printf("(%p)Aut oRef::~AutoRef\ n", (void*)this);
}

public:
AutoRef(AutoRef const&);
AutoRef const& operator =(AutoRef const&);

public:
void Cancel() const throw() {
m_State = 0;
printf("(%p)Aut oRef::Cancel()\ n", (void*)this);
}

public:
T* operator ->() const {
if (! m_State) { throw std::exception( ); }
return m_State;
}

T& operator *() const {
if (! m_State) { throw std::exception( ); }
return *m_State;
}
};
class Foo {
typedef AutoRef<FooAuto Ref_t;

private:
int m_RefCount;

public:
typedef AutoRef_t const &Handle;

static AutoRef_t Create() {
Foo* const This = new Foo;
printf("(%p)Foo ::Create()\n", (void*)This);
return AutoRef_t(This) ;
}

private:
static void Destroy(Foo* const This) {
delete This;
printf("(%p)Foo ::Destroy()\n", (void*)This);
}

public:
Foo() : m_RefCount(1) {
printf("(%p)Foo ::Foo()\n", (void*)this);
}

~Foo() throw() {
printf("(%p)Foo ::~Foo()\n", (void*)this);
}

public:
static void RefCount_XAdd(F oo* const This, int Count) {
if (This) {
--This->m_RefCount;
printf("(%p)Foo ::RefCount_XAdd (%d)\n", (void*)This, Count);
if (This->m_RefCount < 1) {
Destroy(This);
}
}
}

public:
void Test(int State) {
printf("(%p)Foo ::Test(%d)\n", (void*)this, State);
}
};
int main() {
{
Foo::Handle Foo1 = Foo::Create();
Foo1->Test(1);

Foo::Handle Foo2 = Foo1;
Foo2->Test(2);

{
Foo::Handle Foo3 = Foo1;
Foo::Handle Foo4 = Foo2;
Foo3->Test(3);
Foo4->Test(4);
}

Foo1->Test(5);
Foo2->Test(6);
}

printf("\n\n___ _______________ __\npress <ENTERto exit...\n");
getchar();
return 0;
}

----------
Is this legitimate? Or, is the idea basically equal to a pile of pointless
crap!
Any thoughts?

:^)

May 13 '07 #1
0 1277

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