Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of Boost. Click here to view this page for the latest version.


BOOST_FUSION_ADAPT_ASSOC_ADT is a macro than can be used to generate all the necessary boilerplate to adapt an arbitrary class type as a model of Random Access Sequence and Associative Sequence.

    (attribute_type0, attribute_const_type0, get_expr0, set_expr0, key_type0)
    (attribute_type1, attribute_const_type1, get_expr1, set_expr1, key_type1)
Expression Semantics

The above macro generates the necessary code to adapt type_name as a model of Random Access Sequence and Associative Sequence. The sequence of (attribute_typeN, attribute_const_typeN, get_exprN, set_exprN, key_typeN) 5-tuples declares the types, const types, get-expressions, set-expressions and key types of the elements that are part of the adapted fusion sequence. get_exprN is the expression that is invoked to get the Nth element of an instance of type_name. This expression may access a variable named obj of type type_name& or type_name const& which represents the underlying instance of type_name. attribute_typeN and attribute_const_typeN may specify the types that get_exprN denotes to. set_exprN is the expression that is invoked to set the Nth element of an instance of type_name. This expression may access variables named obj of type type_name&, which represent the corresponding instance of type_name, and val of an arbitrary const-qualified reference template type parameter Val, which represents the right operand of the assignment expression.

The actual return type of fusion's intrinsic sequence access (meta-)functions when in invoked with (an instance of) type_name is a proxy type. This type is implicitly convertible to the attribute type via get_exprN and forwards assignment to the underlying element via set_exprN. The value type (that is the type returned by result_of::value_of, result_of::value_of_data, result_of::value_at, result_of::value_at_c and result_of::value_at_key) of the Nth element is attribute_typeN with const-qualifier and reference removed.

The macro should be used at global scope, and type_name should be the fully namespace qualified name of the class type to be adapted.

#include <boost/fusion/adapted/adt/adapt_assoc_adt.hpp>
#include <boost/fusion/include/adapt_assoc_adt.hpp>
namespace demo
    struct employee
        std::string name;
        int age;
        void set_name(std::string const& n)
        void set_age(int a)
        std::string const& get_name()const
            return name;
        int get_age()const
            return age;

namespace keys
    struct name;
    struct age;

    (std::string const&, std::string const&, obj.get_name(), obj.set_name(val), keys::name)
    (int, int, obj.get_age(), obj.set_age(val), keys::age))

demo::employee e;
at_key<keys::name>(e)="Edward Norton";
//Prints 'Edward Norton is 41 years old'
std::cout << e.get_name() << " is " << e.get_age() << " years old" << std::endl;
See also