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Does this leak?

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Started by Storyyeller October 10, 2009 04:01 PM

4 comments, last by Zakwayda 14 years, 6 months ago

Storyyeller

215

Author

October 10, 2009 04:01 PM

What is the proper way to make a vector of an abstract class type with polymorphism? This is the best I could come up with, but I can't help getting the feeling that it is leaking somewhere.


#ifndef SHAREDPOINTER_VECTOR_H
#define SHAREDPOINTER_VECTOR_H

#include "BOOST/shared_ptr.hpp"
#include <cassert>

template <class T>
void AddSmartPointerToVector( std::vector<boost::shared_ptr<T> >& avector, T* aobject)
{
    assert( aobject != NULL);

    boost::shared_ptr<T> newsharedptr(aobject);
    avector.push_back(newsharedptr);
}

#endif


    AddSmartPointerToVector<Brush>( mybrushes, new MultiBlock(0,0,10,1));
    AddSmartPointerToVector<Brush>( mybrushes, new MultiBlock(0,288,10,1));
    AddSmartPointerToVector<Brush>( mybrushes, new MultiBlock(0,32,1,8));
    AddSmartPointerToVector<Brush>( mybrushes, new MultiBlock(288,32,1,8));

I trust exceptions about as far as I can throw them.

Xycaleth

2,391

October 10, 2009 04:05 PM

No, that doesn't leak. By creating a shared_ptr from a raw pointer, the shared_ptr takes ownership of the raw pointer. The shared_ptr will then delete the raw pointer for you, when the shared_ptr is destroyed.

rip-off

11,000

October 10, 2009 04:08 PM

Ideally, you would pass a shared_ptr, rather than a raw pointer. This makes the ownership semantics explicit. You might want to look at boost::make_shared<>() to remove some of the verbosity.

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Storyyeller

215

Author

October 10, 2009 05:05 PM

When I use push_back, does that copy the smart pointer?

I trust exceptions about as far as I can throw them.

rip-off

11,000

October 10, 2009 05:15 PM

Yes. The smart pointer object is copied, but there is no copy of the pointee involved.

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