Maurizio Colucci wrote:
Hello,
I am a newbie user of boost.
I have a question about boost::shared_ptr. Suppose you have a polimorphic list:
class entity{ ...};
class simple_entity : public entity{ public: uint id; simple_entity(uint i) : id(i) {} };
int main(){ list<shared_ptr<entity> > l; ...
I noticed the following code doesn't compile
l.push_back(new simple_entity(1));
too bad, because it was very easy to read, and very similar to the behavior if standard pointers (not to speak about similarity to Java and C#). So I am forced to do
l.push_back(shared_ptr<entity> (new simple_entity(1)));
The idiomatic way to write the above is to use a named variable: shared_ptr<entity> pe(new simple_entity(1)); l.push_back(pe); as explained in http://www.boost.org/libs/smart_ptr/shared_ptr.htm#BestPractices If you want to save typing, consider adding static shared_ptr<simple_entity> create(int id) { shared_ptr<simple_entity> ps(new simple_entity(id)); return ps; } to simple_entity, allowing you to write l.push_back(simple_entity::create(1)); If entity objects are always supposed to live on the heap, you now have the option to make the simple_entity constructor private or protected, leaving 'create' as the only way to obtain a simple_entity.