fused_procedure

| Home | Libraries | People | FAQ | More

#### fused_procedure

##### Description

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

The result is discared and the adapter's return type is `void`.

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 a target function object that is const or, if the target function object is held by value, the adapter is const - these semantics have nothing to do with the const qualification of a member function, which is referring to the type of object pointed to by `this` which is specified with the first element in the sequence passed to the adapter).

If the target function is a pointer to a members function, the corresponding object can be specified as a reference, pointer, or smart pointer. In case of the latter, a freestanding `get_pointer` function must be defined (Boost provides this function for `std::auto_ptr` and `boost::shared_ptr`).

The target function must not be a pointer to a member object (dereferencing such a pointer without returning anything does not make sense, so this case is not implemented).

/functional/adapter/fused_procedure.hpp>

##### Synopsis

    template <typename Function>
    class fused_procedure;

##### Template parameters

Parameter | Description | Default
--- | --- | ---
`Function` | Callable Object type |

##### Model of

- Polymorphic Function Object
- Deferred Callable Object

Notation

`R`

  A possibly const qualified Callable 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_procedure<R>(r)` | Creates a fused function as described above, initializes the target function with `r`.
`fused_procedure<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 SequenceOfSequences, class Func>
    void n_ary_for_each(SequenceOfSequences const & s, Func const & f)
    {
        for_each(zip_view<SequenceOfSequences>(s),
            fused_procedure<Func const &>(f));
    }

    void try_it()
    {
        vector<int,float> a(2,2.0f);
        vector<int,float> b(1,1.5f);
        using namespace boost::lambda;
        n_ary_for_each(vector_tie(a,b), _1 -= _2);
        assert(a == make_vector(1,0.5f));
    }

##### See also

- `fused`
- `fused_function_object`
- `invoke_procedure`