LUMIERA.clone/src/proc/mobject/session/defs-manager.hpp

128 lines
4.6 KiB
C++

/*
DEFS-MANAGER.hpp - access to preconfigured default objects and definitions
Copyright (C) Lumiera.org
2008, Hermann Vosseler <Ichthyostega@web.de>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef MOBJECT_SESSION_DEFS_MANAGER_H
#define MOBJECT_SESSION_DEFS_MANAGER_H
#include "lib/p.hpp"
#include "lib/query.hpp"
#include <boost/scoped_ptr.hpp>
#include <boost/noncopyable.hpp>
namespace mobject {
namespace session {
using lumiera::P;
using boost::scoped_ptr;
namespace impl { class DefsRegistry; }
/**
* Organise a collection of preconfigured default objects.
* For various kinds of objects we can tweak the default parametrisation
* as part of the general session configuration. A ref to an instance of
* this class is accessible through the current session and can be used
* to fill in parts of the configuration of new objects, if the user
* code didn't give more specific parameters. Necessary sub-objects
* will be created on demand, and any default configuration, once
* found, will be remembered and stored with the current session.
*
* @note while the logic of defaults handling can be considered
* roughly final, as of 12/09 most of the actual object
* handling is placeholder code.
*/
class DefsManager : private boost::noncopyable
{
scoped_ptr<impl::DefsRegistry> defsRegistry;
public:
DefsManager () throw();
~DefsManager ();
/** common access point: retrieve the default object fulfilling
* some given conditions. May silently trigger object creation.
* @throw error::Config in case no solution is possible, which
* is considered \e misconfiguration.
*/
template<class TAR>
P<TAR> operator() (lumiera::Query<TAR> const&);
/** search through the registered defaults, never create anything.
* @return object fulfilling the query, \c empty ptr if not found.
*/
template<class TAR>
P<TAR> search (lumiera::Query<TAR> const&);
/** retrieve an object fulfilling the query and register it as default.
* The resolution is delegated to the ConfigQuery system (which may cause
* creation of new object instances)
* @return object fulfilling the query, \c empty ptr if no solution.
*/
template<class TAR>
P<TAR> create (lumiera::Query<TAR> const&);
/** register the given object as default, after ensuring it fulfils the
* query. The latter may cause some properties of the object to be set,
* trigger creation of additional objects, and may fail altogether.
* @return true if query was successful and object is registered as default
* @note only a weak ref to the object is stored
*/
template<class TAR>
bool define (P<TAR> const&, lumiera::Query<TAR> const& =lumiera::Query<TAR>());
/** remove the defaults registration of the given object, if there was such
* @return false if nothing has been changed because the object wasn't registered
*/
template<class TAR>
bool forget (P<TAR> const&);
// Q: can we have something along the line of...?
//
// template
// < class TAR, ///< the target to query for
// template <class> class SMP ///< smart pointer class to wrap the result
// >
// SMP<TAR> operator() (const lumiera::Query<TAR>&);
// 12/09: according to my current knowledge of template metaprogramming, the answer is "no",
// but we could use a traits template to set up a fixed association of smart pointers
// and kinds of target object. This would allow to define a templated operator() returning
// the result wrapped into the right holder. But currently I don't see how to build a sensible
// implementation infrastructure backing such an interface.
//////////TICKET #452
};
}} // namespace mobject::session
#endif