Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

Am 08.12.2012 um 18:43 schrieb Lars Viklund:

On Sat, Dec 08, 2012 at 06:24:08PM +0100, Philipp Kraus wrote:
On 2012-12-08 17:45:07 +0100, Andrew Holden said:
I would ini tialize the shared pointer like so:

boost::shared_ptr <MyType> ptr;

MyType *temp_ptr = cptr_open(); //Use a temporary pointer to avoid  
initializing the shared pointer with null.

if (temp_ptr)
ptr.reset(temp_ptr, &cptr_close);
//Now discard temp_ptr

O  
http://www.boost.org/doc/libs/1_52_0/libs/smart_ptr/shared_ptr.htm#constructors 
I found that I can use a ctor with
template<class Y, class D> shared_ptr(Y * p, D d);
and D is a dtor call. Do you have an example for D ?

'D' can be any type whose value 'd' is callable as d(p). This includes,
but is not limited to:
D: std::function<void (Y*)> // friendly wrapper around callables
D: void (*)(Y*) // regular function pointer to say  void f(Y* p);
D: struct D { void operator () (Y* p) const; };
d: [](Y* p) { .. } // lambdas are neat

In your case, Andrew outlined how you can pass in a function pointer to
your cptr_close, assuming that it has a suitable signature.

The D used in reset() adheres to the same rules as the one in the
constructor your found, namely that it'll be invoked when the last
sibling shared_ptr perishes.


I'm using the ctor call
boost::shared_ptr<mycptr> x ( cptr_open(), cptr_close );

this seems to be working at the moment

Thx

Phil

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