DisplayParameter.h

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//# DisplayParameter.h: base class for storing and parsing parameters
//# Copyright (C) 2000,2001
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library 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 Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//#        Internet email: aips2-request@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA
//#
//# $Id$

#ifndef TRIALDISPLAY_DISPLAYPARAMETER_H
#define TRIALDISPLAY_DISPLAYPARAMETER_H

#include <casa/aips.h>
#include <casa/Containers/Record.h>
#include <display/Utilities/DisplayOptions.h>

namespace casa { //# NAMESPACE CASA - BEGIN

// <summary>
// Base class for storing and parsing of parameters for display classes.
// </summary>

// <use visibility=local>

// <reviewed reviewer="" date="" test="" demos="">
// </reviewed>

// <prerequisite>
// <li> <linkto class=DisplayOptions>DisplayOptions</linkto>
// </prerequisite>

// <etymology>
// DisplayParameter is a base class which provides services for
// conveniently storing and parsing parameters relevant to the display
// classes.
// </etymology>

// <synopsis>
// DisplayParameter defines a relatively simple interface for writing
// small containers for the various types of parameters used
// throughout the display classes.  The required interface consists of
// methods to update the parameter value from an incoming
// <src>RecordInterface</src>-type object, and to add the description
// of the parameter to a provided <src>RecordInterface</src> object.
//
// Other than this, all parameters share these common elements:
//
// <li> <src>name</src>, a short <src>String</src> uniquely
// identifiying the parameter.
//
// <li> <src>description</src>, a slightly longer <src>String</src>
// which offers a description of the parameter, suitably short for
// display in a graphical user interface, for example.
//
// <li> <src>help</src>, an even longer <src>String</src> (!) which
// should be filled in with text describing the option in more detail
// than can be given in <src>description</src>
//
// <li> <src>context</src>, which if provided (ie. <src>context !=
// String("")</src>) gives a category name for this parameter, and is
// used, for example, by the autogui to place the parameter in an
// appropriately named roll-up.
//
// <li> <src>allowunset</src>, which indicates whether this parameter
// can be "unset" or not.  An "unset" parameter is one for which a
// sensible (perhaps context sensitive) default can be determined and
// used.  Derived classes need not provide this option in their
// constructor.
//
// <li> <src>editable</src>, which indicates whether this parameter is
// allowed to be modified by the user.
//
// DisplayParameter makes use of the <linkto
// class=DisplayOptions>DisplayOptions</linkto> class to parse Records
// containing parameter descriptions.  Derived classes must implement
// the two virtual methods <src>toRecord</src> and
// <src>fromRecord</src>, which respectively store a description of
// the DisplayParameter in a sub-field of the provided
// RecordInterface, and extract the value of the DisplayParameter from
// a sub-field in the provided record.  The sub-field is identified by
// the <src>name</src> of the DisplayParameter.
//
// Derived classes should also add utility functions which return the
// various aspects of the DisplayParameter to the programmer.  Most
// importantly, a <src>value()</src> function should be provided to
// enable the user to easily retrieve the current value of the
// parameter.
// </synopsis>

// <motivation>
// To avoid littering many of the display classes with code fragments
// for constructing and parsing Records.
// </motivation>

// <thrown>
// <li> None.
// </thrown>

// <todo asof="2000/01/28">
// <li> Provide base class support for unset values.
// </todo>

        class DisplayParameter {

        public:

                // Destructor.
                virtual ~DisplayParameter();

                // Parse <src>record</src>, and update this parameter if a field
                // exists whose name matches that of this parameter.  Return
                // <src>True</src> if the parameter is changed, otherwise return
                // <src>False</src>.
                virtual Bool fromRecord(const RecordInterface &record) = 0;

                // Place a record describing this parameter in a sub-field of
                // <src>record</src> with name matching that of this parameter.  If
                // <src>overwrite</src> is <src>True</src>, then any existing field
                // with matching name will be overwritten.  If <src>fullrecord</src>
                // is <src>True</src>, then a complete description of the parameter
                // is given, otherwise just its current value is stored in
                // <src>record</src>.
                virtual void toRecord(RecordInterface &record, const Bool fullrecord = True,
                                      const Bool overwrite = False) = 0;

                // Return the name of this parameter.
                String name() const {
                        return itsName;
                }

                // Return the description of this parameter.
                String description() const {
                        return itsDescription;
                }

                // Return the help for this parameter.
                String help() const {
                        return itsHelp;
                }

                // Return the context of this parameter.
                String context() const {
                        return itsContext;
                }

                // Return whether this parameter can be unset.
                Bool allowUnset() const {
                        return itsAllowUnset;
                }

                // Return whether this parameter is editable.
                Bool editable() const {
                        return itsEditable;
                }

                // Set or change the name of this parameter to that specified.
                void setName(const String name) {
                        itsName = name;
                }

                // Set or change the description of this parameter to what is
                // specified.
                void setDescription(const String description) {
                        itsDescription = description;
                }

                // Set or change the help for this parameter to what is specified.
                void setHelp(const String help) {
                        itsHelp = help;
                }

                // Set or change the context of this parameter to what is specified.
                void setContext(const String context) {
                        itsContext = context;
                }

                // Set or change whether this parameter may be unset, according to
                // the function argument value.
                void setAllowUnset(const Bool allowunset) {
                        itsAllowUnset = allowunset;
                }

                // Set or change whether this parameter is editable according to
                // the function argument.
                void setEditable(const Bool editable) {
                        itsEditable = editable;
                }

        protected:

                // Constructor taking the name of the parameter, a short
                // description, some help text, and flags indicating whether the
                // parameter can be unset and is editable.
                DisplayParameter(const String name, const String description,
                                 const String help, const String context = "",
                                 const Bool allowunset = False,
                                 const Bool editable = True);

                // Copy constructor using copy semantics.
                DisplayParameter(const DisplayParameter &other);

                // Default constructor yielding a useless DisplayParameter.
                DisplayParameter();

                // Copy assignment.
                DisplayParameter &operator=(const DisplayParameter &other);

                // Return a basic description of this parameter; used by virtual
                // implementations of <src>toRecord</src> method to fill out
                // a Record describing this DisplayParameter.
                Record baseDescription();

                // Return the DisplayOptions to use for parsing Records.
                const DisplayOptions &displayOptions() const {
                        return itsDisplayOptions;
                }

        private:

                // Store for the name of this parameter.
                String itsName;

                // Store for the description of this parameter.
                String itsDescription;

                // Store for the help for this parameter.
                String itsHelp;

                // Store for the context of this parameter.
                String itsContext;

                // Store for whether this parameter can be unset.
                Bool itsAllowUnset;

                // Store for whether this parameter is editable.
                Bool itsEditable;

                // Store for a DisplayOptions object for parsing Records.
                DisplayOptions itsDisplayOptions;

        };


} //# NAMESPACE CASA - END

#endif