gears::utility::any Class Reference

A class that contains a type erased value. More...

Public Member Functions
	any () noexcept=default
	Constructs any with no value. More...
template<typename T >
	any (T &&actual) noexcept
	Constructs any with a value. More...
	any (const any &other)
	Copy constructor.
	any (any &&other)
	Move constructor. Must not throw.
any &	operator= (const any &other)
	Copy assignment.
any &	operator= (any &&other)
	Move assignment. The value of other is removed.
	operator bool () const
	Checks if any is in a proper state. More...
template<typename T >
bool	is () const
	Checks if the value of any is a certain type. More...
template<typename T >
const Decayed< T > &	as () const
	Casts any to access the contained value. More...
template<typename T >
Decayed< T > &	as ()

Related Functions
(Note that these are not member functions.)
template<typename T >
auto	any_cast (const any &object) -> decltype(object.as< T >())
	Helper function to cast any. More...

Detailed Description

any is a class that can contain most type of variables assuming they are copy constructible. This is similar to other dynamic typing languages where you could assign any type to a variable. The closest C++ alternative to this behaviour would be using a void* but any does this in a safer manner without having void pointers.

Example:

#include <gears/utility/any.hpp>
#include <iostream>
#include <vector>

namespace util = gears::utility;

int main() {
     std::vector<util::any> stuff = { "hello", "world", '!', 1.0f, 200.0, 10 };
     for(auto&& i : stuff) {
         if(i.is<const char*>()) {
             std::cout << i.as<const char*>() << ' ';
         }

         if(i.is<char>()) {
             std::cout << i.as<char>() << '\n';
         }

         if(i.is<int>()) {
             std::cout << i.as<int>() * 150 << '\n';
         }
     }
}

Output:

hello world !
1500

Definition at line 82 of file any.hpp.

Constructor & Destructor Documentation

gears::utility::any::any ( )

defaultnoexcept

Constructs any with no value. Accessing it with its empty state is undefined behaviour.

template<typename T >

gears::utility::any::any ( T &&  actual )

inlinenoexcept

Constructs any with a value. After construction, any holds the value contained and can be accessed with is with the type of the variable provided. The type passed must be copy constructible or else a compiler error will be thrown.

Parameters

actual

Value to construct any with.

Definition at line 128 of file any.hpp.

Member Function Documentation

template<typename T >

const Decayed<T>& gears::utility::any::as ( ) const

inline

Casts any to access the contained value. In order to check if the type is valid use is.

Template Parameters

T	Type to cast to.

Exceptions

gears::utility::bad_any_cast

Thrown if the type is invalid.

Returns

The value contained if they type is valid.

Definition at line 200 of file any.hpp.

template<typename T >

bool gears::utility::any::is ( ) const

inline

Checks if the value of any is a certain type. A specific gotcha with this function is thinking the value of a string literal is std::string, it is actually const char*. This function should be called before calling as.

Template Parameters

T	Type to check for.

Returns

true if the internal value is of type T, false otherwise.

Definition at line 184 of file any.hpp.

gears::utility::any::operator bool ( ) const

inlineexplicit

Checks if any is in a proper state, i.e. it contain a value.

Returns

true is any contains a value, false otherwise.

Definition at line 168 of file any.hpp.

Friends And Related Function Documentation

template<typename T >

auto any_cast ( const any &  object ) -> decltype(object.as<T>())

related

Helper function to cast any to another type.

Parameters

object

The object to cast.

Template Parameters

T	The type to cast to.

Exceptions

gears::utility::bad_any_cast

Thrown if the type is invalid.

Returns

The value contained in the object if the type is valid.

Definition at line 228 of file any.hpp.