ClickHouse/base/poco/Foundation/include/Poco/Void.h

//
// Void.h
//
// Library: Foundation
// Package: Core
// Module:  Void
//
// Definition of the Void class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_Void_INCLUDED
#define Foundation_Void_INCLUDED


#include "Poco/Foundation.h"


namespace Poco
{


class Foundation_API Void
/// A dummy class with value-type semantics,
/// mostly useful as a template argument.
///
/// This class is typically used together with ActiveMethod,
/// if no argument or return value is needed.
{
public:
    Void();
    /// Creates the Void.

    Void(const Void & v);
    /// Creates the Void from another Void.
    ///
    /// The philosophical aspects of this operation
    /// remain undiscussed for now.

    ~Void();
    /// Destroys the Void.

    Void & operator=(const Void & v);
    /// Assigns another void.

    bool operator==(const Void & v) const;
    /// Will return always true due to Voids having no members.

    bool operator!=(const Void & v) const;
    /// Will return always false due to Voids having no members.
};


inline bool Void::operator==(const Void & /*v*/) const
{
    return true;
}


inline bool Void::operator!=(const Void & /*v*/) const
{
    return false;
}


} // namespace Poco


#endif // Foundation_Void_INCLUDED