fused_function

fused_function_object

Description

An unary Polymorphic Function Object adapter template for a Polymorphic Function Object target function. It takes a Forward Sequence that contains the arguments for the target function.

The nested result metafunction is inhertied from the target function.

The type of the target function is allowed to be const qualified or a reference. Const qualification is preserved and propagated appropriately (in other words, only const versions of operator() can be used for an target function object that is const or, if the target function object is held by value, the adapter is const).

Header

#include <boost/fusion/functional/adapter/fused_function_object.hpp>

Synopsis

template <class Function>
class fused_function_object;

Template parameters

Parameter	Description	Default
`Function`	Polymorphic Function Object type

Model of

Notation

R: A possibly const qualified Polymorphic Function Object type or reference type thereof
r: An object convertible to R
s: A Sequence of arguments that are accepted by r
f: An instance of fused<R>

Expression Semantics

Expression	Semantics
`fused_function_object<R>(r)`	Creates a fused function as described above, initializes the target function with `r`.
`fused_function_object<R>()`	Creates a fused function as described above, attempts to use `R`'s default constructor.
`f(s)`	Calls `r` with the elements in `s` as its arguments.

Example

template<class SeqOfSeqs, class Func>
typename result_of::transform< zip_view<SeqOfSeqs> const,
    fused_function_object<Func const &> >::type
n_ary_transform(SeqOfSeqs const & s, Func const & f)
{
    return transform(zip_view<SeqOfSeqs>(s), 
        fused_function_object<Func const &>(f));
} 

struct sub
{
    template<typename T, typename _>
    struct result
    {
        typedef T type;
    };

    template<typename T>
    T operator()(T lhs, T rhs) const
    {
        return lhs - rhs;
    }
};

void try_it()
{
    vector<int,float> a(2,2.0f);
    vector<int,float> b(1,1.5f);
    vector<int,float> c(1,0.5f);
    assert(c == n_ary_transform(vector_tie(a,b), sub()));
}