Description

boost::result_of has some problems especially under Boost1.34 or below:

So that, Egg provides its own "result_of" with slightly different name.

	Caution
	If you already use Boost1.35 and don't pass a cv-qualified function pointer, you don't need this workaround.

	Note
	The former bug can probably be worked around by applying a patch to Boost.ResultOf.

Header

Valid expressions

See also

Description

BOOST_MPL_HAS_XXX_TRAIT_DEF, which Boost.ResultOf and Boost.Lambda depend on, sometimes fails to work under the msvc compilers. When you see a weird error message such that "nested sig template is undefined" or "nested result template is undefined", use this header.

	Note
	This bug can probably be worked around by applying a patch to Boost.Lambda and Boost.ResultOf.

Header

Valid expressions

Preconditions

See also

Description

When you define a Function Object in namespace scope, GCC might show unused variable warnings without this macro.

	Tip
	Strictly speaking, a const-qualified object in namespace scope incurs ODR(One Definition Rule) violation. Though a conforming workaround is found, even GCC can't do the right thing around address constant expression. Anyway, it is unlikely for this violation to cause significant problem.

Header

Valid expressions

Preconditions

Example

BOOST_EGG_CONST((T_foo), foo) = &foo_impl;

Description

Under GCC 3.4.x, when you overload call in Little Function with the same arity, the following workaround is needed to disambiguate overload resolution.

Header

Valid expressions

Preconditions

Example

struct little_foo
{
    BOOST_EGG_OVERLOADED_PREAMBLE() 

    template<class Me, class A1>
    struct apply
    {
        typedef A1 &type;
    };

    template<class Re, class A1>
    Re call(BOOST_EGG_OVERLOADED(Re) A1 &a1) const 
    {
        return a1;
    }

    template<class Re, class A1>
    Re call(BOOST_EGG_OVERLOADED(Re) A1 const &a1) const
    {
        return a1;
    }
};

	Egg turns on the workaround if this macro is found.
	Notice there is no trailing comma.

See also