std::enable_shared_from_this::operator=

From cppreference.com
C++
Utilities library
Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Library feature-test macros
Date and time
Function objects
(C++11)
(C++11)
(C++14)
Relational operators (deprecated)
Comparisons (C++20)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++17)
(C++17)

Swap, forward and move
(C++14)
(C++11)
(C++11)
(C++11)
Elementary string conversions
(C++17)
(C++17)
(C++17)
Type operations
(C++11)
(C++17)
Dynamic memory management
Uninitialized storage
(C++17)
(until C++20)
(until C++20)
(until C++20)
Garbage collection support
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Miscellaneous
(C++11)
(C++20)
(C++11)
(C++11)
C Library
Low level memory management
std::enable_shared_from_this
enable_shared_from_this<T>& operator=( const enable_shared_from_this<T> &obj ) noexcept;
 (since C++11)

Does nothing; returns *this.

Parameters

obj - an enable_shared_from_this to assign to *this

Return value

*this

Notes

The private std::weak_ptr<T> member is not affected by this assignment operator.

Example

Note: enable_shared_from_this::operator= is defined as protected in order to prevent accidental slicing but allow derived classes to have default assignment operators.

Run this code
#include <memory>
#include <iostream>

class SharedInt : public std::enable_shared_from_this<SharedInt>
{
public:
    explicit SharedInt(int n) : mNumber(n) {}
    SharedInt(const SharedInt&) = default;
    SharedInt(SharedInt&&) = default;
    ~SharedInt() = default;

    // Both assignment operators use enable_shared_from_this::operator=
    SharedInt& operator=(const SharedInt&) = default;
    SharedInt& operator=(SharedInt&&) = default;

    int number() const { return mNumber; }

private:
    int mNumber;
};

int main() {
    std::shared_ptr<SharedInt> a = std::make_shared<SharedInt>(2);
    std::shared_ptr<SharedInt> b = std::make_shared<SharedInt>(4);
    *a = *b;

    std::cout << a->number() << std::endl;
}

Output: 

4

See also

(C++11)
 smart pointer with shared object ownership semantics
(class template)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/memory/enable_shared_from_this/operator%3D&oldid=93243"