cbe::util::Optional< T > Class Template Reference

Class template Optional manages an optional contained value - i.e., a value that is either present or absent. More...

#include <Optional.h>

Classes
class	BadAccess
	Thrown by value() method when accessing an object that does not contain a value. More...

Public Member Functions
	Optional ()=default
	Creates an empty Optional, i.e., no value present.
	Optional (const T &value)
	Copy value ctor.
	Optional (T &&value) noexcept(std::is_nothrow_move_constructible< T >::value)
	Move value ctor.
	Optional (const Optional &rh)
	Copy ctor.
	Optional (Optional &&rh) noexcept(std::is_nothrow_move_constructible< T >::value)
	Move ctor.
Optional &	operator= (const Optional &rh)
	Copy assignment operator.
Optional &	operator= (Optional &&rh) noexcept
	Move assignment operator.
T &	value ()
	Value access non-const method.
T &	operator* ()
T *	operator-> ()
const T &	value () const
	Value access const method.
const T &	operator* () const
const T *	operator-> () const
bool	hasValue () const noexcept
	Checks whether a value is present.
	operator bool () const noexcept
	Checks whether a value is present. More...
void	reset ()
	Invalidates possible contained value. The contained value will be destructed.
void	swap (Optional &other) noexcept
	Swaps the contents with those of other.
template<typename... ArgTs>
void	emplace (ArgTs &&... args)
	Constructs the contained value in-place. If *this already contains a value before the call, the contained value is destroyed by calling its destructor.

Detailed Description

template<typename T>
class cbe::util::Optional< T >

Class template Optional manages an optional contained value - i.e., a value that is either present or absent.

Template Parameters

T	Type of the contained value

Member Function Documentation

operator bool()

template<typename T >

cbe::util::Optional< T >::operator bool ( ) const

inlineexplicitnoexcept

Checks whether a value is present.

cbe::util::Optional<int> inquireInt(const char* prompt) {
  while (true) {
    std::cout << prompt << ": ";
    std::string answer;
    std::cin >> answer;
    try {
      return std::stoi(answer); // I.e., return cbe::util::Optional<int>{std::stoi(answer)}
    }
    catch (...) {
      // Invalid input
      return {}; // I.e., return cbe::util::Optional<int>{};
    }
  }
}
~~~
auto n = inquireInt("Please, give an integer value");
if (n) {
  std::cout << "Thanks for the number" << *n << "!\n";
} else {
  std::cout << "Not a number!\n";
}
~~~

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The documentation for this class was generated from the following file:

• include/cbe/util/Optional.h