Re: [Boost-users] boost shared_ptr with own dtor

Subject: Re: [Boost-users] boost shared_ptr with own dtor
From: Philipp Kraus (philipp.kraus_at_[hidden])
Date: 2012-12-08 13:03:02

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