Description

This macro must follow the local function body code block { ... }:

{ // Some declarative context.
    ...
    result_type BOOST_LOCAL_FUNCTION(declarations) {
        ... // Body code.
    } BOOST_LOCAL_FUNCTION_NAME(qualified_name)
    ...
}

Within templates, the special macros BOOST_LOCAL_FUNCTION_TPL and BOOST_LOCAL_FUNCTION_NAME_TPL must be used.

Parameters:

name:
        [inline] [recursive] local_function_name

The local function name can be qualified by prefixing it with the keyword inline (see the Advanced Topics section):

BOOST_LOCAL_FUNCTION_NAME(inline local_function_name)

This increases the chances that the compiler will be able to inline the local function calls (thus reducing run-time). However, inline local functions cannot be passed as template parameters (e.g., to std::for_each) or assigned to other functors (e.g., to boost::function). That is true on C++03 compilers but inline local functions can instead be passed as template parameters on C++11 compilers. On C++11 compilers, there is no need to declare a local function lined because this library will automatically use C++11 specific features to inline the local function while always allowing to pass it as a template parameter. This optimization is automatically enabled when the Boost.Config macro BOOST_NO_CXX11_LOCAL_CLASS_TEMPLATE_PARAMETERS is not defined but it also be forced using BOOST_LOCAL_FUNCTION_CONFIG_LOCALS_AS_TPARAMS.

The local function name can also be qualified by prefixing it with the "keyword" recursive (see the Advanced Topics section):

BOOST_LOCAL_FUNCTION_NAME(recursive local_function_name)

This allows the local function to recursively call itself from its body (as usual in C++). However, recursive local functions should only be called within their declaration scope (otherwise the result is undefined behaviour). Finally, compilers have not been observed to be able to inline recursive local function calls, not even when the recursive local function is also declared inline:

BOOST_LOCAL_FUNCTION(inline recursive local_function_name)

Note: The local function name cannot be the name of an operator operator... and it cannot be the same name of another local function declared within the same enclosing scope (but boost::overloaded_function can be used to overload local functions, see Boost.Functional/OverloadedFunction and the Advanced Topics section).

See: Tutorial section, Advanced Topics section, BOOST_LOCAL_FUNCTION, BOOST_LOCAL_FUNCTION_NAME_TPL.