Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
std::experi...urce_checked(3) C++ Standard Libarystd::experi...urce_checked(3)

NAME
       std::experimental::make_unique_resource_checked	  -    std::experimen-
       tal::make_unique_resource_checked

Synopsis
	  Defined in header <experimental/scope>
	  template< class R, class D, class S =	std::decay_t<R>	>

	  std::experimental::unique_resource<std::decay_t<R>,
	  std::decay_t<D>>
       (library
	      make_unique_resource_checked(  R&&  r,  const  S&	 invalid,  D&&
       fundamentals TS v3)
	  d )

	      noexcept(/*see below*/);

	  Creates a unique_resource, initializes its stored resource handle is
       initialized
	  with std::forward<R>(r) and its deleter with std::forward<D>(d). The
       created
	  unique_resource  owns	the resource if	and only if bool(r == invalid)
       is false.

	  The program is ill-formed if the expression r	== invalid  cannot  be
       contextually
	  converted  to	 bool, and the behavior	is undefined if	the conversion
       results in
	  undefined behavior or	throws an exception.

Exceptions
	  Any exception	thrown in initialization of the	stored resource	handle
       and the
	  deleter.

	  noexcept specification:
	  noexcept(

	      std::is_nothrow_constructible_v<std::decay_t<R>, R> &&
	      std::is_nothrow_constructible_v<std::decay_t<D>, D>

	  )

Notes
	  make_unique_resource_checked exists to avoid calling a deleter func-
       tion with an
	  invalid argument.

	  Resource handle r is either copied or	moved into the	return	value,
       and the created
	  unique_resource  always holds	an underlying resource handle with ob-
       ject type.

Example
       // Run this code

	#include <cstdio>
	#include <experimental/scope>

	int main()
	{
	    // avoid calling fclose when fopen fails
	    auto file =	std::experimental::make_unique_resource_checked(
		std::fopen("potentially_nonexistent_file.txt", "r"),
		nullptr,
		[](std::FILE *fptr) { std::fclose(fptr); }
	    );
	    if (file.get())
		std::puts("The file exits.");
	    else
		std::puts("The file does not exist.");
	}

Possible output:
	The file does not exist.

See also
Category:
	    * conditionally noexcept

http://cppreference.com		  2024.06.10	 std::experi...urce_checked(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::experimental::make_unique_resource_checked&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>

home | help