Re: prevent assignement from a vector

mosfet <>
Fri, 05 Oct 2007 09:55:13 +0200
Barry a ?crit :

mosfet wrote:


In one my class I would like to give access to one of my buffer so I
have declared something like this :

vector<char>& RespData = pWebResp->get_RawBuffer();

I guess that you have a member of vector<char> in pWebResp.
assume that pWebResp is of WebResp* type;
then you can let /WebResp/ non-copyable by declare /operator=/ and
copy-ctor private members of /WebResp/.

The problem is caller can also write this :

vector<char> RespData = pWebResp->get_RawBuffer();

Oh, then you have to use a wrapper for std::vector<char>
class NonCopyVector
  : public std::vector<char>
  NonCopyVector(NonCopyVector const&);
  NonCopyVector& operator= (NonCopyVector const&);

I guess someone will say, don't inherit from vector.

but why bot just use

vector<char>* pResp = pWebResp->get_RawBuffer();
// return pointer then reference

If you still likes return by reference


class VectorRef
   typedef std::vector<char>& ref_type;
   VectorRef(ref_type ref) : ref_(ref) {}
   operator ref_type() { return ref_; }
   ref_type ref_;

VectorRef dataRef = pWebResp->get_RawBuffer();

but you have to explicit cast to std::vector<char>& type before calling
its member functions



IMO, change to return pointer is better.

and in this case will it copy my buffer into RespData ?
If yes how can I prevent this behavior ?

Thanks a lot for this full answer!!!

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