Posted by
Yan Kuang on
URL: http://quantlib.414.s1.nabble.com/reference-of-boost-shared-ptr-instead-of-Handle-tp7623p7629.html
Luigi Ballabio <[hidden email]> wrote
on 02/09/2009 07:33:35 PM:
> On Wed, 2009-09-02 at 14:31 +1000, Yan Kuang wrote:
> > I am not sure I understand, do you mean point to a different
object.
> > Shared pointer
> > can do too:
> >
> > void f (boost::shared_ptr<T> & pA)
> > {
> > boost::shared_ptr<T> pB(new T);
> >
> > pA = pB;
> > }
>
> Yes, but try this:
>
> #include <iostream>
>
> class T {
> int i_;
> public:
> T(int i) : i_(i) {}
> int i() const { return i_; }
> };
>
> class Foo {
> shared_ptr<T> p_;
> public:
> Foo(const shared_ptr<T>& p) : p_(p) {}
> void check() const {
> std::cout << p_->i() <<
std::endl;
> }
> };
>
> int main() {
> boost::shared_ptr<T> pA(new T(1));
> Foo f(pA);
> f.check(); // prints 1
>
> boost::shared_ptr<T> pB(new T(2));
> pA = pB; // you're changing pA, but not
the copy
> // stored
by the Foo object
> f.check(); // in fact, this still prints 1
> }
>
This because constructor of Foo called copy constructor of boost::shared_ptr.
f.p_ is just a copy of pA.
So Handle behaves like a raw pointer. I can see YieldTermStructure,
Quote etc using handle
in Quantlib code, I can see the reason now.
Thanks,
Yan
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