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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>, (library std::decay_t<D>> fundamentals TS v3) make_unique_resource_checked(R&& r, const S& invalid, D&& 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. Paramaters r - a resouce handle d - a deleter to use to dispose the resource invalid - a value indicating the resource handle is invalid Reture value A unique_resource described above. 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 http://cppreference.com 2022.07.31 std::experi...urce_checked(3)
NAME | Synopsis | Exceptions | Notes | Example | Possible output: | See also
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