Re: Force creation of objects with new operator

From:

Urs Thuermann <urs@isnogud.escape.de>

Newsgroups:

comp.lang.c++

Date:

07 Jul 2011 13:15:42 +0200

Message-ID:

<ygfhb6y1gv5.fsf@janus.isnogud.escape.de>

Jorgen Grahn <grahn+nntp@snipabacken.se> writes:

On Thu, 2011-06-30, Urs Thuermann wrote:

I have a class where I want objects to commit suicide by calling

delete this;

...

Is this considered a clean approach? Are there better ways?

There are likely better ways, but /which ones/ depends on your
particular problem, and you haven't shown that one. It seems to me a
communication path from your class is missing, or something -- it
cannot tell its environment "I'm done now; you may destroy me".

In my code I have a class A that has one pointer to an object of class
B and each object of B has list of pointers to all objects of class A
refering to it. Therefore, this is similar to a reference couting
smart pointer but I need the list of referers in class B. That's why
I didn't implement it in a separate smart pointer class:

        class A;

        class B {
                std::list <A *> refs;
                ~B() { ... }
        public:
                B(A *a) {
                        add_ref(a);
                }
                void add_ref(A *a) {
                        refs.push_back(a);
                }
                void rem_ref(A *a) {
                        refs.remove(a);
                        if (refs.empty())
                                delete this;
                }
        };

        class A {
                B *b;
        public:
                A(...) {
                        if (b = find_matching_B(...))
                                b->add_ref(this);
                        else
                                b = new B(this);
                }
                ~A() {
                        b->rem_ref(this);
                }
        };

Currently, I don't see how a wrapper around B that deletes the B
objects could make this cleaner.

urs