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std::weak_ptr

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< cpp‎ | memory

 
 
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initializer_list(C++11)
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Smart pointers
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C Library
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std::weak_ptr
メンバ関数
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Member functions
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weak_ptr::weak_ptr
weak_ptr::~weak_ptr
weak_ptr::operator=
修飾子
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Modifiers
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weak_ptr::reset
weak_ptr::swap
オブザーバー
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Observers
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weak_ptr::use_count
weak_ptr::expired
weak_ptr::lock
weak_ptr::owner_before
非メンバ関数
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Non-member functions
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std::swap
 
Defined in header <memory>
template< class T > class weak_ptr;
(C++11およびそれ以降)
std::weak_ptrstd::shared_ptrによって管理されているオブジェクトへの非所有( "弱い")の参照を保持しているスマートポインタです。それにアクセスするためにstd::shared_ptrに変換する必要があります参照されるオブジェクト.
Original:
std::weak_ptr is a smart pointer that holds a non-owning ("weak") reference to an object that is managed by std::shared_ptr. It must be converted to std::shared_ptr in order to access the referenced object.
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std::weak_ptrモデル一時的に所有:オブジェクトが存在する場合にのみアクセスする必要がある、それは他の誰かがいつでも削除することができるときに、std::weak_ptrは、オブジェクトを追跡するために使用され、それがstd::shared_ptrに変換されます一時的な所有権を想定する。元std::shared_ptrはこの時点で破壊された場合は一時的なstd::shared_ptrも同様に破棄されるまで、オブジェクトの生存期間が延長される.
Original:
std::weak_ptr models temporary ownership: when an object needs to be accessed only if it exists, and it may be deleted at any time by someone else, std::weak_ptr is used to track the object, and it is converted to std::shared_ptr to assume temporary ownership. If the original std::shared_ptr is destroyed at this time, the object's lifetime is extended until the temporary std::shared_ptr is destroyed as well.
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また、std::weak_ptrstd::shared_ptr.
Original:
In addition, std::weak_ptr is used to break circular references of std::shared_ptr.
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目次

[編集] メンバータイプ

メンバー·タイプ
Original:
Member type
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Definition
element_type T

[編集] メンバ関数

新しいweak_ptrを作成します
Original:
creates a new weak_ptr
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(パブリックメンバ関数) [edit]
weak_ptrを破棄します
Original:
destroys a weak_ptr
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(パブリックメンバ関数) [edit]
weak_ptrを割り当てます
Original:
assigns the weak_ptr
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(パブリックメンバ関数) [edit]
修飾子
Original:
Modifiers
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管理対象オブジェクトの所有権を解放します
Original:
releases the ownership of the managed object
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(パブリックメンバ関数) [edit]
スワップの管理対象オブジェクト
Original:
swaps the managed objects
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(パブリックメンバ関数) [edit]
オブザーバー
Original:
Observers
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オブジェクトを管理shared_ptrオブジェクトの数を返します
Original:
returns the number of shared_ptr objects that manage the object
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(パブリックメンバ関数) [edit]
参照されるオブジェクトが既に削除されたかどうかをチェックします
Original:
checks whether the referenced object was already deleted
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(パブリックメンバ関数) [edit]
参照されるオブジェクトを管理shared_ptrを作成します
Original:
creates a shared_ptr that manages the referenced object
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(パブリックメンバ関数) [edit]
ウィークポインタの所有者ベースのオーダーを提供しています
Original:
provides owner-based ordering of weak pointers
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(パブリックメンバ関数) [edit]

[編集] 非メンバ関数

std::swapアルゴリズムを専門としています
Original:
specializes the std::swap algorithm
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(関数テンプレート) [edit]

[編集]

を示します。。どのようにロックがポインタの妥当性を確保するために使用され.
Original:
Demonstrates how lock is used to ensure validity of the pointer.
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#include <iostream>
#include <memory>
 
std::weak_ptr<int> gw;
 
void f()
{
    if (auto spt = gw.lock()) { // Has to be copied into a shared_ptr before usage
	std::cout << *spt << "\n";
    }
    else {
        std::cout << "gw is expired\n";
    }
}
 
int main()
{
    {
        auto sp = std::make_shared<int>(42);
	gw = sp;
 
	f();
    }
 
    f();
}

Output:

42
gw is expired