Variant< _num, _TypeMap > Class Template Reference

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Detailed Description

template<int _num, typename _TypeMap>
class lemon::Variant< _num, _TypeMap >

Simple Variant type. The Variant type is a type safe union. The C++ has strong limitations for using unions, by example we cannot store type with non default constructor or destructor in a union. This class always knowns the current state of the variant and it cares for the proper construction and destruction.

Parameters:

	_num	The number of the types which can be stored in the variant type.
	_TypeMap	This class describes the types of the Variant. The _TypeMap::Map<index>::Type should be a valid type for each index in the range {0, 1, ..., _num - 1}. The VariantTypeMap is helper class to define such type mappings up to 10 types.

And the usage of the class:

      typedef Variant<3, VariantTypeMap<int, std::string, double> > MyVariant;
      MyVariant var;
      var.set<0>(12);
      std::cout << var.get<0>() << std::endl;
      var.set<1>("alpha");
      std::cout << var.get<1>() << std::endl;
      var.set<2>(0.75);
      std::cout << var.get<2>() << std::endl;

The result of course:

      12
      alpha
      0.75

#include <lemon/bits/variant.h>

List of all members.

Public Member Functions
	Variant ()
	Constructor.
	Variant (const Variant &variant)
	Copy constructor.
Variant &	operator= (const Variant &variant)
	Assign operator.
	~Variant ()
	Destrcutor.
template<int _idx>
Variant &	set ()
	Set to the default value of the type with _idx index.
template<int _idx>
Variant &	set (const typename _TypeMap::template Map< _idx >::Type &init)
	Set to the given value of the type with _idx index.
template<int _idx>
const TypeMap::template Map < _idx >::Type &	get () const
template<int _idx>
_TypeMap::template Map< _idx > ::Type &	get ()
int	state () const

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Constructor & Destructor Documentation

Variant

(

)

[inline]

This constructor initalizes to the default value of the type with 0 index.

Variant

(

const Variant< _num, _TypeMap > &

variant

)

[inline]

Copy constructor

~Variant

(

)

[inline]

Destructor

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Member Function Documentation

Variant& operator=

(

const Variant< _num, _TypeMap > &

variant

)

[inline]

Assign operator

Variant& set

(

)

[inline]

This function sets the variant to the default value of the type with _idx index.

Variant& set

(

const typename _TypeMap::template Map< _idx >::Type &

init

)

[inline]

This function sets the variant to the given value of the type with _idx index.

const TypeMap::template Map<_idx>::Type& get

(

)

const [inline]

Gets the current value of the type with _idx index.

_TypeMap::template Map<_idx>::Type& get

(

)

[inline]

Gets the current value of the type with _idx index.

int state

(

)

const [inline]

Returns the current state of the variant.