Thread: vector<*C> and vector<C>

Hello,

I have writen a lot of functions working on containers of objects. Now I've decided it's better not to copy the objects in the containers, but to use conteiners of pointers.

Is there some solution in which I do not have to wewrite all my functions?

Thanks,
Angy

vector<some_object *> my_pointers_to_several_objects ;

Of course I meant vector<C*> it was a typing mistake, sorry.

Vectors of references do not exist. The reason is that a reference is just an alternative name for an object, so that makes no sense.

Any other Ideas?

Are you talking about not wanting to change your code from object.variable to object->variable?

Todd

Originally Posted by anon

None of the objects in the containers need to be copied if you pass the vector to the functions as a reference.

But objects are copied on insertion into containers

Originally Posted by Todd Burch

Are you talking about not wanting to change your code from object.variable to object->variable?

Todd

you can put it that way

I do not want to go to every function and change

my_vector_of_obgects[i]

to

*(my_vector_of_pointers_to_obgects[i])

whenever a single object from a container is passed to another function

I suspect if you do as ANON suggested, and change your functions to pass as a reference, that would satisfy your objective.

I did what you don't want to do a couple weeks ago - it was a pain. The DOT notation is easier to read. I may try ANON's suggestion as well.

Todd

Originally Posted by Todd Burch

I suspect if you do as ANON suggested, and change your functions to pass as a reference, that would satisfy your objective.

I did what you don't want to do a couple weeks ago - it was a pain. The DOT notation is easier to read. I may try ANON's suggestion as well.

Todd

I think there is a missunderstanding here:

The problem is not that I am not passing the container as reference to functions, but that I do not want to copy on insertion and thus use containers of pointers now.

E.g.

vector<int> vi;
int i;
vi.push_back(i);
// here i is copied into vi
// &vi[0] is not the address of i

Originally Posted by laserlight

From what I see boost::ptr_vector is designed to allow that kind of syntax (i.e., you do not need to change the code to use dereference pointers).


If Angelina is indeed working with large objects for which copying is expensive, the overhead of having to copy on insertion may be too much. Of course, this assumes that some profiling was done, which is why I asked for the basis for the decision to change to use containers of pointers.

I'm not very familiar with the boost library and not keen on mixing that in now.

I was wondering if there is any more "standard" solution?

Yes, my objects are too big to be OK to copy

OK, I understand. (I'm not a C++ expert, if you haven't figured that out yet).

Why won't this work:

vector<int *> vi;
int i;
vi.push_back(&i);

?