The type of result returned by library functions
template<
class T>
using result = result<T, error_code> ;
Declared in file <boost/url/error_types.hpp> at line 280
This alias is no longer supported and should not be used in new code. Please use `system::result` instead.
This alias is included for backwards compatibility with earlier versions of the library.
However, it will be removed in future releases, and using it in new code is not recommended.
Please use the updated version instead to ensure compatibility with future versions of the library.
template< class T >
class result
{
public:
//
// Return true if the result contains an error
//
constexpr bool has_error() const noexcept;
//
// Return the error
//
constexpr system::error_code error() const noexcept;
//
// Return true if the result contains a value
//
constexpr bool has_value() const noexcept;
constexpr explicit operator bool() const noexcept;
//
// Return the value, or throw an exception
//
constexpr T& value();
constexpr T const& value() const;
// Return the value.
// Precondition: has_value()==true
//
constexpr T& operator*() noexcept;
constexpr T* operator->() noexcept;
constexpr T const& operator*() const noexcept;
constexpr T const* operator->() const noexcept;
...more
Given the function parse_uri with this signature:
system::result< url_view > parse_uri( core::string_view s ) noexcept;
The following statement captures the value in a variable upon success, otherwise throws:
url_view u = parse_uri( "http://example.com/path/to/file.txt" ).value();
This statement captures the result in a local variable and inspects the error condition:
system::result< url_view > rv = parse_uri( "http://example.com/path/to/file.txt" );
if(! rv )
std::cout << rv.error();
else
std::cout << *rv;