Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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Function call

boost::type_erasure::call

Synopsis

// In header: <boost/type_erasure/call.hpp>


template<typename Concept, typename Op, class... U> 
  unspecified call(const binding< Concept > & binding, const Op &, 
                   U &&... args);
template<typename Op, class... U> unspecified call(const Op &, U &&... args);

Description

Dispatches a type erased function.

Op must be a primitive concept which is present in Concept. Its signature determines how the arguments of call are handled. If the argument is a placeholder, call expects an any using that placeholder. This any is unwrapped by call. The type that it stores must be the same type specified by binding. Any arguments that are not placeholders in the signature of Op are passed through unchanged.

If binding is not specified, it will be deduced from the arguments. Naturally this requires at least one argument to be an any. In this case, all any arguments must have the same binding.

Example:

* typedef mpl::vector<
*   copy_constructible<_b>,
*   addable<_a, int, _b> > concept;
* any<concept, _a> a = ...;
* any<concept, _b> b(call(addable<_a, int, _b>(), a, 10));
* 

The signature of addable is _b(const _a&, const int&)

Returns:

The result of the operation. If the result type of the signature of Op is a placeholder, the result will be converted to the appropriate any type.

Throws:

bad_function_call if relaxed is in Concept and there is a type mismatch.

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