VariantO< TYPES, Access > Class Template Reference

#include "lib/variant-o.hpp"

Description

template<typename TYPES, template< typename > class Access>
class lib::VariantO< TYPES, Access >

A variant wrapper (typesafe union) capable of holding a value of any of a bounded collection of types.

The value is stored in a local buffer directly within the object and may be accessed by a typesafe visitation.

This utility class is similar to boost::variant and indeed was implemented (5/08) in an effort to replace the latter in a draft solution for the problem of typesafe access to the correct wrapper class from within some builder tool. Well – after finishing this "exercise" I must admit that it is not really much more simple than what boost::variant does internally. At least we are pulling in fewer headers and the actual code path is shorter compared with boost::variant, at the price of being not so generic, no care for alignment issues within the buffer or for thread safety.

Deprecated:

immature first design attempt. obsolete. Please use lib::Variant ////////////////TICKET #738

Parameters

TYPES	collection of possible types to be stored in this variant object
Access	policy how to access the stored value

Definition at line 244 of file variant-o.hpp.

Public Member Functions
template<typename TAR >
TAR	get ()
	retrieve current content of the variant, trying to cast or convert it to the given type. More...
template<typename SRC >
VariantO &	operator= (SRC src)
	store a copy of the given argument within the variant holder buffer, thereby typically casting or converting the given source type to the best suited (base) type (out of the collection of possible types for this VariantO instance)
void	reset ()

Private Types
typedef Holder::Deleter	Deleter
typedef variant::Holder< TYPES >	Holder

Private Attributes
Holder::Storage	holder_
	storage: buffer holding either an "empty" marker, or an instance of one of the configured payload types

Additional Inherited Members
Private Member Functions inherited from NonCopyable
	NonCopyable (NonCopyable const &)=delete
NonCopyable &	operator= (NonCopyable const &)=delete

Member Function Documentation

get()

TAR get ( )

inline

retrieve current content of the variant, trying to cast or convert it to the given type.

Actually, the function access(T&) on the Access-policy (template param) is invoked with the type currently stored in the holder buffer. May return NULL if conversion fails.

Definition at line 284 of file variant-o.hpp.

Referenced by WrappedStandardExeBuilder::__call__().

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Inheritance diagram for VariantO< TYPES, Access >:

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

• variant-o.hpp