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## Macro Metafunctions

The TTI library uses macros to create metafunctions, in the current scope, for introspecting an inner element by name. Each macro for a particular type of inner element has two forms, the simple one where the first macro parameter designating the 'name' of the inner element is used to create the name of the metafunction, and the complex one where the first macro parameter, called 'trait', designates the name of the metafunction and the second macro parameter designates the 'name' to be introspected. Other than that difference, the two forms of the macro create metafunctions which have the exact same functionality.

To use these metafunctions you can include the main general header file 'boost/tti/tti.hpp', unless otherwise noted. Alternatively you can include a specific header file as given in the table below.

A table of these macros is given, based on the inner element whose existence the metaprogrammer is introspecting. More detailed explanations and examples for each of the macro metafunctions will follow this section in the documentation. The actual syntax for each macro metafunction can be found in the reference section, and examples of usage for all the macro metafunctions can be found in the "Using the Macro Metafunctions" section.

In the Template column only the name generated by the simple form of the template is given since the name generated by the complex form is always 'trait' where 'trait' is the first parameter to the corresponding complex form macro.

All of the introspecting metafunctions in the table below return a boolean constant called 'value', which specifies whether or not the inner element exists. All of the metafunctions also have a nested type called 'type', which for each one is the type of the boolean constant value. This is always boost::mpl::bool_.

Table 1.2. TTI Macro Metafunctions

Inner Element | Macro | Template | Specific Header File
--- | --- | --- | ---
Type | `BOOST_TTI_HAS_TYPE`(name) | `has_type_'name'` class TTI_T = enclosing type | `has_type.hpp`
Type with lambda expression | `BOOST_TTI_HAS_TYPE`(name) | `has_type_'name'` class TTI_T = enclosing type class TTI_U = lambda expression invoked with the inner type and returning a boolean constant | `has_type.hpp`
Class Template ( using variadic macros ) | `BOOST_TTI_HAS_TEMPLATE`(name) | `has_template_'name'` class TTI_T = enclosing type All of the template parameters must be template type parameters ( 'class' or 'typename' parameters ) | `has_template.hpp`
Class Template ( not using variadic macros ) | `BOOST_TTI_HAS_TEMPLATE`(name,BOOST_PP_NIL) | `has_template_'name'` class TTI_T = enclosing type All of the template parameters must be template type parameters ( 'class' or 'typename' parameters ) | `has_template.hpp`
Class Template with params ( using variadic macros ) | `BOOST_TTI_HAS_TEMPLATE`(name,...[a]) | `has_template_'name'` class TTI_T = enclosing type | `has_template.hpp`
Class Template with params | `BOOST_TTI_HAS_TEMPLATE`(name,ppArray[b]) | `has_template_'name'` class TTI_T = enclosing type | `has_template.hpp`
Member data | `BOOST_TTI_HAS_MEMBER_DATA`(name) | `has_member_data_'name'` class TTI_T = enclosing type OR pointer to member data ( 'MemberData_Type Enclosing_Type::*' ) class TTI_R = (optional) data type If the first parameter is the pointer to member data this must not be specified. | `has_member_data.hpp`
Member function | `BOOST_TTI_HAS_MEMBER_FUNCTION`(name) | `has_member_function_'name'` class TTI_T = enclosing type OR pointer to member function ( 'Return_Type Enclosing_Type::* ( Zero or more comma-separated parameter types )' ) class TTI_R = (optional) return type if the first parameter is the enclosing type. If the first parameter is the pointer to member function this must not be specified. class TTI_FS = (optional) function parameter types as a Boost MPL forward sequence. If the first parameter is the pointer to member function this must not be specified. If there are no function parameters this does not have to be specified. Defaults to boost::mpl::vector<>. class TTI_TAG = (optional) Boost `function_types` tag type. If the first parameter is the pointer to member function this must not be specified. Defaults to `boost::function_types::null_tag`. | `has_member_function.hpp`
Static member data | `BOOST_TTI_HAS_STATIC_MEMBER_DATA`(name) | `has_static_member_data_'name'` class TTI_T = enclosing type class TTI_Type = data type | `has_static_member_data.hpp`
Static member function | `BOOST_TTI_HAS_STATIC_MEMBER_FUNCTION`(name) | `has_static_member_function_'name'` class TTI_T = enclosing type class TTI_R = return type OR function type ( 'Return_Type (Zero or more comma-separated parameter types)' ) class TTI_FS = (optional) function parameter types as a Boost MPL forward sequence. If the second parameter is the function type this must not be specified. If there are no function parameters, this does not have to be specified. Defaults to boost::mpl::vector<>. class TTI_TAG = (optional) Boost `function_types` tag type. If the second parameter is the function type this must not be specified. Defaults to `boost::function_types::null_tag`. | `has_static_member_function.hpp`
Data, either member data or static member data | `BOOST_TTI_HAS_DATA`(name) | `has_data_'name'` class TTI_T = enclosing type class TTI_Type = data type | `has_data.hpp`
Function, either member function or static member function | `BOOST_TTI_HAS_FUNCTION`(name) | `has_function_'name'` class TTI_T = enclosing type class TTI_R = return type class TTI_FS = (optional) function parameter types as a Boost MPL forward sequence. If there are no function parameters, this does not have to be specified. Defaults to boost::mpl::vector<>. class TTI_TAG = (optional) Boost `function_types` tag type. Defaults to `boost::function_types::null_tag`. | `has_function.hpp`
[a] The template parameters as variadic data. [b] The template parameters as the tuple part of the PP array.