imported>Unknown at 05:22, 7 February 2021

2021-02-07T05:22:38Z

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스마트 포인터 쓰기
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== 설치 ==
* [http://boost.org/ boost] 에 가서 다운받고 설치한다.
* boost 라이브러리는 헤더 파일만이 존재한다. 모든 구현을 헤더 파일에 해 놓았기 때문이다. 바로 필살 헤더와 구현 분리하기 귀잖어 기술....본인은 애용한다...

== shared_ptr ==
* new 를 해주고 delete 하는 것 에서 해방을!
* 표준 라이브러리에도 auto_ptr 이라고 같은 개념의 클래스가 있지만, 버그가 있다. -_-;; auto_ptr를 컨테이너에 집어넣으면 버그땜시 스스로 삭제가 안되 메모리가 새는 아주 심각한 문제이다.
...
#include <boost/smart_ptr.hpp>
...
using namespace boost;
...
class Vertex3D {...}
typedef shared_ptr<Vertex3D> Vertex3DSPtr;
typedef vector<Vertex3DSPtr> Vertexs; // 단어 틀렸다는거 알지만 그냥 씀 -_-
typedef Vertexs::size_type VertexsSize;
typedef Vertexs::iterator VertexsItr;
typedef shared_ptr<Vertexs> VertexsSPtr;
...
{
VertexsSPtr vertexs(new Vertexs);
Vertex3DSPtr vertex(new Vertex3D);
...
vertexs->push_back(vertex);
...
}
* new 를 했지만 delete 를 안해도 지가 알아서 사라진다.
* 모든 객체에 스마트포인터를 쓰도록 프로그램 짜면 자바같은 느낌으로 짤수도 ...

=== shared_ptr_example ===
shared_ptr_example.cpp
// Boost shared_ptr_example.cpp --------------------------------------------//

// (C) Copyright Beman Dawes 2001. Permission to copy,
// use, modify, sell and distribute this software is granted provided this
// copyright notice appears in all copies. This software is provided "as is"
// without express or implied warranty, and with no claim as to its
// suitability for any purpose.

// See http://www.boost.org for most recent version including documentation.

// Revision History
// 21 May 01 Initial complete version (Beman Dawes)

// The original code for this example appeared in the shared_ptr documentation.
// Ray Gallimore pointed out that foo_set was missing a Compare template
// argument, so would not work as intended. At that point the code was
// turned into an actual .cpp file so it could be compiled and tested.

#include <vector>
#include <set>
#include <iostream>
#include <algorithm>
#include <boost/shared_ptr.hpp>

// The application will produce a series of
// objects of type Foo which later must be
// accessed both by occurrence (std::vector)
// and by ordering relationship (std::set).

struct Foo
{
Foo( int _x ) : x(_x) {}
~Foo() { std::cout << "Destructing a Foo with x=" << x << "\n"; }
int x;
/* ... */
};

typedef boost::shared_ptr<Foo> FooPtr;

struct FooPtrOps
{
bool operator()( const FooPtr & a, const FooPtr & b )
{ return a->x > b->x; }
void operator()( const FooPtr & a )
{ std::cout << a->x << "\n"; }
};

int main()
{
std::vector<FooPtr> foo_vector;
std::set<FooPtr,FooPtrOps> foo_set; // NOT multiset!

FooPtr foo_ptr( new Foo( 2 ) );
foo_vector.push_back( foo_ptr );
foo_set.insert( foo_ptr );

foo_ptr.reset( new Foo( 1 ) );
foo_vector.push_back( foo_ptr );
foo_set.insert( foo_ptr );

foo_ptr.reset( new Foo( 3 ) );
foo_vector.push_back( foo_ptr );
foo_set.insert( foo_ptr );

foo_ptr.reset ( new Foo( 2 ) );
foo_vector.push_back( foo_ptr );
foo_set.insert( foo_ptr );

std::cout << "foo_vector:\n";
std::for_each( foo_vector.begin(), foo_vector.end(), FooPtrOps() );

std::cout << "\nfoo_set:\n";
std::for_each( foo_set.begin(), foo_set.end(), FooPtrOps() );
std::cout << "\n";

// Expected output:
//
// foo_vector:
// 2
// 1
// 3
// 2
//
// foo_set:
// 3
// 2
// 1
//
// Destructing a Foo with x=2
// Destructing a Foo with x=1
// Destructing a Foo with x=3
// Destructing a Foo with x=2

return 0;
}

=== shared_ptr_example2 ===
shared_ptr_example2.hpp (헉 이너클래스가 되네.. 처음봤다 --;;)
// Boost shared_ptr_example2 header file -----------------------------------//

#include <boost/shared_ptr.hpp>

// This example demonstrates the handle/body idiom (also called pimpl and
// several other names). It separates the interface (in this header file)
// from the implementation (in shared_ptr_example2.cpp).

// Note that even though example::implementation is an incomplete type in
// some translation units using this header, shared_ptr< implementation >
// is still valid because the type is complete where it counts - in the
// shared_ptr_example2.cpp translation unit where functions requiring a
// complete type are actually instantiated.

class example
{
public:
example();
example( const example & );
example & operator=( const example & );
void do_something();
private:
class implementation;
boost::shared_ptr< implementation > _imp; // hide implementation details
};

shared_ptr_example2.cpp
// Boost shared_ptr_example2 implementation file -----------------------------//

#include "shared_ptr_example2.hpp"
#include <iostream>

class example::implementation
{
public:
~implementation() { std::cout << "destroying implementation\n"; }
};

example::example() : _imp( new implementation ) {}
example::example( const example & s ) : _imp( s._imp ) {}

example & example::operator=( const example & s )
{ _imp = s._imp; return *this; }

void example::do_something()
{ std::cout << "use_count() is " << _imp.use_count() << "\n"; }

shared_ptr_example2_test.cpp
// Boost shared_ptr_example2_test main program ------------------------------//

#include "shared_ptr_example2.hpp"

int main()
{
example a;
a.do_something();
example b(a);
b.do_something();
example c;
c = a;
c.do_something();
return 0;
}

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See Also [http://dalsu.80port.net/wiki/wiki.php/boost/shared_ptr Boost의 shared_ptr]

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BoostLibrary

BoostLibrary/SmartPointer - Revision history

imported>Unknown at 05:22, 7 February 2021