Re: Inherit from vector, encapsulate, or not bother?

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 16 Apr 2008 11:23:14 -0400
Message-ID:
<fu55l2$gmc$1@news.datemas.de>
nw wrote:

I currently have a vector of objects (lets call them MyObject). I want
to perform various operations regularly on the whole vector, for
example find the maximum, average, or operations not dissimilar to
that. So as I see it I have 3 options:

1. Implement these operations as functions


Looks like a very good first step. If you find it unnecessary to do
either of the two below, you just leave those alone and keep using them
and if you decide to have your own container class, you can still
incorporate those as member functions (or call them from some member
functions)...

2. Derive a class from vector (from googling people seem to think this
is a bad idea)


It depends. If your new container is not going to "specialise" the
vector (so to speak), then derive away. Inheritance is a mechanism
and the usefulness of it is in the eye of the beholder.

3. Encapsulate the vector in an object.


....or privately inherit the vector. Either way, you're implementing
your object "in terms of the vector". There is a bit more freedom
in that (versus deriving), but, again, it's debatable, and depends.

I'm tending toward option 1 at the moment and perhaps making my
functions generic?


Sounds like a good idea.

What does comp.lang.c++ think?


<shrug> We never seem to think exactly the same thing... <g>

Any advice appreciated!

#include <iostream>
#include <vector>

using namespace std;

class MyObject {

 int v1;
 int v2;
 int v3;
};

class MyObjectSet {
 public:

 vector<MyObject> vec;

 int max() {
   // Would find maximum value in o

   return 1;
 }
};

int main() {
 MyObject o;

 MyObjectSet s;

 s.vec.push_back(o);

}


V
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