callback_r_0.h

Go to the documentation of this file.

/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
 *  
 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
 *  others to use your version of this file under the CPAL, indicate your decision by 
 *  deleting the provisions above and replace them with the notice and other 
 *  provisions required by the GPL License. If you do not delete the provisions above,
 *  a recipient may use your version of this file under either the CPAL or the GPL.
 *  
 *  *** END LICENSE INFORMATION ***
 */



/** @class lass::util::CallbackR0
 *  @ingroup Callback
 *  @brief callback with 0 parameters but with returnvalue.
 *  @date 2002
 *  @author Bram de Greve [Bramz] (contact: bramz@users.sourceforge.net)
 *
 *  It's a single object that can hold a reference to a free function or an
 *  object/(const) method pair.  Once the callback is constructed, it works
 *  completely transparent.  All it shows to the client is a function that
 *  takes 0 parameter(s) and gives a returnvalue.
 */



#ifndef LASS_GUARDIAN_OF_INCLUSION_UTIL_CALLBACK_R_0_H
#define LASS_GUARDIAN_OF_INCLUSION_UTIL_CALLBACK_R_0_H



// --- OLD INTERFACES ----------------------------------------------------------

#include "util_common.h"
#include "shared_ptr.h"
#include "callback_common.h"
#include "impl/dispatcher_r_0.h"




// --- NEW INTERFACES ----------------------------------------------------------

namespace lass
{
namespace util
{


// THE CALLBACK:
// This is the actuall class you use to hold callbacks:

template
<
    typename R
>
class CallbackR0
{
public:

    typedef CallbackR0<R> TSelf;
    typedef SharedPtr< impl::DispatcherR0<R> > TDispatcherPtr;

    // STRUCTORS

    /** Default constructor, construct empty callback.
     */
    CallbackR0()
    {
    }

    /** Construct function callback
     */
    template <typename Function>
    CallbackR0(Function iFunction):
        dispatcher_(make(iFunction, meta::Wrap<typename meta::IsDerived<Function, impl::DispatcherR0<R> >::Type>()))
    {
    }

    /** Construct object/method callback.
     */
    template <typename ObjectPtr, typename Method>
    CallbackR0(ObjectPtr iObject, Method iMethod):
        dispatcher_(new impl::DispatcherR0Method<R, ObjectPtr, Method>(iObject, iMethod))
    {
    }

    /** copy constructor
     */
    CallbackR0(const TSelf& iOther):
        dispatcher_(iOther.dispatcher_)
    {
    }



    // OPERATORS

    /** assignment operator
     */
    template <typename Other>
    TSelf& operator=(const Other& iOther)
    {
        TSelf temp(iOther);
        swap(temp);
        return *this;
    }

    /** THE operator.  Executes the callback.
     */
    R operator()() const
    {
        if (isEmpty())
        {
            LASS_THROW_EX(EmptyCallback, "You've tried to call an empty CallbackR0.  Can't return a value.");
        }
        return dispatcher_->call();
    }


    // METHODS

    /** Reset to empty callback.
     */
    void reset()
    {
        dispatcher_.reset();
    }

    /** Returns true if no callback dispatcher is assigned to this object.
     */
    bool isEmpty() const
    {
        return dispatcher_.isEmpty();
    }

    /** return this->isEmpty()
     */
    bool operator!() const
    {
        return dispatcher_.isEmpty(); 
    }

    /** return !this->isEmpty())
     */
    operator num::SafeBool() const
    {
        return dispatcher_.isEmpty() ? num::safeFalse : num::safeTrue;
    }

    /** Swaps the dispatcher of this callback with the dispatcher of another.
     */
    void swap(TSelf& iOther)
    {
        dispatcher_.swap(iOther.dispatcher_);
    }

private:

    template <typename Function>
    static TDispatcherPtr make(Function iFunction, meta::Wrap<meta::False>)
    {
        return TDispatcherPtr(new impl::DispatcherR0Function<R, Function>(iFunction));
    }

    template <typename Dispatcher>
    static TDispatcherPtr make(Dispatcher iDispatcher, meta::Wrap<meta::True>)
    {
        return TDispatcherPtr(new Dispatcher(iDispatcher));
    }

    TDispatcherPtr dispatcher_;
};



/** return true if two callbacks are different
 *  @relates CallbackR0
 */
template <typename R>
bool operator!=(const CallbackR0<R>& iA, const CallbackR0<R>& iB)
{
    return !(iA == iB);
}



/** make a CallbackR0 from a function
 *  @relates CallbackR0
 */
template <typename R> inline
CallbackR0<R> makeCallback(R (*iFunction)())
{
    return Callback0(iFunction);
}



/** make a CallbackR0 from a callback
 *  @relates CallbackR0
 */
template <typename R> inline
const CallbackR0<R>& makeCallback(const CallbackR0<R>& iCallback)
{
    return iCallback;
}



/** make a CallbackR0 from a object and method
 *  @relates CallbackR0
 */
template <typename ObjectPtr, typename Object, typename R> inline
CallbackR0<R> makeCallback(ObjectPtr iObject, R (Object::*iMethod)())
{
    return Callback0(iObject, iMethod);
}



/** make a CallbackR0 from a object and const method
 *  @relates CallbackR0
 */
template <typename ObjectPtr, typename Object, typename R> inline
CallbackR0<R> makeCallback(ObjectPtr iObject, R (Object::*iMethod)() const)
{
    return Callback0(iObject, iMethod);
}



}

}

#define LASS_PRIM_HAVE_PY_EXPORT_TRAITS_CALLBACK_R0
#ifdef LASS_GUARDIAN_OF_INCLUSION_UTIL_CALLBACK_PYTHON_H
#   include "callback_python.h"
#endif

#endif // Guardian of Inclusion

// EOF