folgender code:

#include <utility>
#include <cmath>
#include <memory>
#include <type_traits>
#include <functional>
#include <map>
#include <initializer_list>
#include <iostream>

using arg_t = double;

struct callable_t
{
	virtual ~callable_t() = default;
	virtual arg_t invoke( arg_t const* args ) const = 0;
};
template< typename T >
class one_arg_t : public callable_t
{
	T m_obj;

public:
	template< typename... args_t >
	one_arg_t( args_t&&... args )
		: m_obj( std::forward< args_t >( args )... )
	{
	}

	virtual arg_t invoke( arg_t const* args ) const override
	{
		return m_obj( args[0] );
	}
};
template< typename T >
auto make_one_arg( T&& obj )
{
	return std::move( std::make_unique< one_arg_t< std::decay_t< T > > >( std::forward< T >( obj ) ) );
}
template< typename T >
class two_args_t : public callable_t
{
	T m_obj;

public:
	template< typename... args_t >
	two_args_t( args_t&&... args )
		: m_obj( std::forward< args_t >( args )... )
	{
	}

	virtual arg_t invoke( arg_t const* args ) const override
	{
		return m_obj( args[0], args[1] );
	}
};
template< typename T >
auto make_two_args( T&& obj )
{
	return std::move( std::make_unique< two_args_t< std::decay_t< T > > >( std::forward< T >( obj ) ) );
}

class callables_t
{
	std::map< std::size_t, std::unique_ptr< callable_t > > m_callables;

public:
	template< typename T, typename U >
	void insert( T&& k, U&& v )
	{
		m_callables.insert( decltype( m_callables )::value_type{ std::forward< T >( k ), std::forward< U >( v ) } );
	}

	arg_t invoke( std::size_t n, arg_t const* args ) const
	{
		const auto finding = m_callables.find( n );
		if( finding == m_callables.end() )
		{
			throw std::logic_error{ "invalid number of arguments" };
		}
		return finding->second->invoke( args );
	}
};

int main()
{
	callables_t callables;
	callables.insert( 1, make_one_arg( static_cast< arg_t( * )( arg_t )>( &std::sin ) ) );
	callables.insert( 2, make_two_args( static_cast< arg_t( * )( arg_t, arg_t )>( &std::atan2 ) ) );
	const std::array< arg_t, 2 > args{ 3.14159265 / 2, args[ 0 ] };
	std::cout << callables.invoke( 1, args.data() ) << '\n';
	std::cout << callables.invoke( 2, args.data() ) << '\n';
}

ich benutze hier one_arg_t und two_args_t um einen pointer auf argumente 'zu entpacken'. faellt euch eine moeglichkeit ein, wie ich das so abaendern kann, dass ich nur noch die anzahl an parametern als template-argument uebergeben kann, so dass danach der pointer automatisch 'extrahiert' wird, wie oben zu sehen in z.b. zeile 53?

danke im voraus, lg