|
|
On 04/22/05 08:00:04, Joseph Wang wrote:
> Could someone add to the wiki or the web, a style guide on pointers. I'm
> a little confused over what Handle is being used for and if this is
> prefered over the boost pointers or not.
They serve two different purposes. A shared_ptr is the smart equivalent of
a pointer. A Handle is the equivalent of a pointer to pointer. The
difference is as follows:
class Foo {};
class Bar {
boost::shared_ptr<Foo> f_;
public:
Bar(boost::shared_ptr<Foo> f) : f_(f) {}
};
class Baz {
Handle<Foo> f_;
public:
Baz(Handle<Foo> f) : f_(f) {}
};
boost::shared_ptr<Foo> f1(new Foo); // points to a Foo object X
Bar bar(f1); // bar.f_ points to the same Foo object Y
f1 = boost::shared_ptr<Foo>(new Foo);
// after the above, f1 points to a new Foo object Y,
// while bar.f_ still points to X.
Handle<Foo> f2(boost::shared_ptr<Foo>(new Foo)); // points to a Foo Z
Baz baz(f2); // baz.f_ points to Z too
f2.linkTo(boost::shared_ptr<Foo>(new Foo));
// after the above, f2 points to a new Foo object W,
// and baz.f_ points to the new W as well.
This allows one, for instance, to instantiate a number of bonds passing
them copies of a Handle to a yield term structure. Later, linking the
handle to another term structure causes all bonds to see the change and
recalculate their price accordingly.
Later,
Luigi
----------------------------------------
The purpose of abstraction is not to be vague, but to create a new
semantic level in which one can be absolutely precise.
-- W.E. Dijkstra
|
Locked
