Struct _byval

Boost C++ Libraries

Struct _byval

boost::proto::_byval — A unary callable PolymorphicFunctionObject that strips references and boost::reference_wrapper<> from its argument.

Synopsis

// In header: <boost/proto/transform/arg.hpp>


struct _byval :  proto::callable {
  // member classes/structs/unions
  template<typename This, typename T> 
  struct result<This(boost::reference_wrapper< T >)> :  result<This(T)> {
  };
  template<typename This, typename T> 
  struct result<This(T &)> :  result<This(T)> {
  };
  template<typename This, typename T> 
  struct result<This(T)> {
    // types
    typedef T type;
  };

  // public member functions
  template<typename T> T operator()(T const &) const;
  template<typename T> 
    T operator()(boost::reference_wrapper< T > const &) const;
};

Description

Example:

proto::terminal<int>::type i = {42};
int j = 67;
int k = proto::when<proto::_, proto::_byval(proto::_state)>()(i, boost::ref(j));
assert( 67 == k );

`_byval` public member functions

```
template<typename T> T operator()(T const & t) const;
```
Parameters:

t

The object to unref

Returns:

t

Throws:
Will not throw.
```
template<typename T> 
  T operator()(boost::reference_wrapper< T > const & t) const;
```
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.