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
I think you mean vector<C*> instead of vector<*C>.vector<*C> and vector<C>
On what basis did you make your decision?Now I've decided it's better not to copy the objects in the containers, but to use conteiners of pointers.
I do not think so. Once you use a vector of pointers you have to think about memory management. Things like boost::ptr_vector may be able to help, but there will still be quite some re-writing to do, methinks.Is there some solution in which I do not have to wewrite all my functions?
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
vector<some_object *> my_pointers_to_several_objects ;
Perhaps you could try a vector of reference but I'm not even sure it exists (never done it or seen it). It's worth a try. I don't think this would work because of the container's processing of the elements but try and see if it works =)
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?
None of the objects in the containers need to be copied if you pass the vector to the functions as a reference.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.
I might be wrong.
Quoted more than 1000 times (I hope).Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
But objects are copied on insertion into containers
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
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 suspect if you do as ANON suggested, and change your functions to pass as a reference, that would satisfy your objective.
Last edited by laserlight; 01-04-2008 at 12:30 PM.
Look up a C++ Reference and learn How To Ask Questions The Smart Way
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
Boost. People who won't use it are masochists.
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
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);
?
