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std::unique_ptr::reset(3)      C++ Standard Libary     std::unique_ptr::reset(3)

NAME
     std::unique_ptr::reset - std::unique_ptr::reset

Synopsis
	members of the primary template, unique_ptr<T>
	void  reset(  pointer  ptr = pointer() ) noexcept;  (1) (constexpr since
     C++23)
	members of the specialization unique_ptr<T[]>
	template< class U >				  (2)  (constexpr  since
     C++23)
	void reset( U ptr ) noexcept;
	void  reset(  std::nullptr_t  = nullptr ) noexcept; (3) (constexpr since
     C++23)

	Replaces the managed object.

	1) Given current_ptr, the pointer that was managed  by	*this,	performs
     the following
	actions, in this order:
	 1. Saves a copy of the current pointer old_ptr = current_ptr.
	 2. Overwrites the current pointer with the argument current_ptr = ptr.
	 3. If the old pointer was non-empty, deletes the previously managed ob-
     ject if
	    (old_ptr) get_deleter()(old_ptr).
	2)  Behaves the same as the reset member of the primary template, except
     that it will
	only participate in overload resolution if either
	 1. U is the same type as pointer, or
	 2. pointer is the same type as element_type* and U is a pointer type V*
     such that
	    V(*)[] is convertible to element_type(*)[].
	3) Equivalent to reset(pointer()).

Parameters
	ptr - pointer to a new object to manage

Return value
	(none)

Notes
	To replace the managed object while supplying a  new  deleter  as  well,
     move assignment
	operator may be used.

	A test for self-reset, i.e. whether ptr points to an object already man-
     aged by
	*this,	is  not performed, except where provided as a compiler extension
     or as a
	debugging assert. Note that code such as p.reset(p.release())  does  not
     involve
	self-reset, only code like p.reset(p.get()) does.

Example
     // Run this code

      #include <iostream>
      #include <memory>

      struct Foo // object to manage
      {
	  Foo() { std::cout << "Foo...\n"; }
	  ~Foo() { std::cout << "~Foo...\n"; }
      };

      struct D // deleter
      {
	  void operator() (Foo* p)
	  {
	      std::cout << "Calling delete for Foo object... \n";
	      delete p;
	  }
      };

      int main()
      {
	  std::cout << "Creating new Foo...\n";
	  std::unique_ptr<Foo, D> up(new Foo(), D()); // up owns the Foo pointer
     (deleter D)

	  std::cout << "Replace owned Foo with a new Foo...\n";
	  up.reset(new Foo());	// calls deleter for the old one

	  std::cout << "Release and delete the owned Foo...\n";
	  up.reset(nullptr);
      }

Output:
      Creating new Foo...
      Foo...
      Replace owned Foo with a new Foo...
      Foo...
      Calling delete for Foo object...
      ~Foo...
      Release and delete the owned Foo...
      Calling delete for Foo object...
      ~Foo...

	Defect reports

	The  following	behavior-changing  defect  reports were applied retroac-
     tively to
	previously published C++ standards.

	   DR	 Applied to		 Behavior as published		    Cor-
     rect behavior
	LWG 2118 C++11	    unique_ptr<T[]>::reset rejected qualification    ac-
     cepts
			    conversions

See also
	release  returns a pointer to the managed object and releases the owner-
     ship
		(public member function)

http://cppreference.com 	   2024.06.10	       std::unique_ptr::reset(3)
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