std::experimental::make_unique_resource_checked(3)

NAME
std::experimental::make_unique_resource_checked - std::experimental::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 function 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 object 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