#ifndef acsexmplLongDevIO_h #define acsexmplLongDevIO_h /******************************************************************************* * ALMA - Atacama Large Millimiter Array * (c) European Southern Observatory, 2002 * Copyright by ESO (in the framework of the ALMA collaboration) * and Cosylab 2002, All rights reserved * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * * "@(#) $Id: acsexmplLongDevIO.h,v 1.11 2008/10/09 08:41:11 cparedes Exp $" * * who when what * -------- -------- ---------------------------------------------- * david 2003-10-20 created */ #ifndef __cplusplus #error This is a C++ include file and cannot be used from plain C #endif ///Need the defition of the class to inherit from #include #include /** @file acsexmplLongDevIO.h */ /** @addtogroup ACSEXMPLTOC */ /*@{ */ /** @defgroup ACSEXMPLTOMISCELLANEOUS Miscellaneous Examples */ /*@{ */ /** @defgroup ACSEXMPLLONGDEVIODOC Long DevIO Subclass * @{ * @htmlonly

Description

This example should prove to be particularly useful to those developers dealing directly with hardware. The full implementation of a DevIO subclass is presented here and it's usage can be found in the Ramped Power Supply example. DevIOs should be used when you need to keep a BACI property read-only, but also have to change the value of the property dynamically.

What can I gain from this example?

  • the complete implementation of a DevIO subclass.
  • limited asynchronous error handling.


Links



@endhtmlonly * @} */ /* @}*/ /* @}*/ /** * This class provides an example of the implementation of a devIO subclass. Developers * should use devIOs when you have a BACI property where you need to change the underlying value, * but do not want the property to be read-write where anyone can change it. Please see the * Ramped Power Supply example to see how this class is used in conjunction with BACI long * properties. * @version "@(#) $Id: acsexmplLongDevIO.h,v 1.11 2008/10/09 08:41:11 cparedes Exp $" */ class acsexmpl_EXPORT LongDevIO : public DevIO { public: /** * Default constuctor - nothing to do. */ LongDevIO() {}; /** * Destructor - nothing to destroy. */ virtual ~LongDevIO() {}; /** * ??? * @return True if the value has been initialized. * @htmlonly
@endhtmlonly */ virtual bool initializeValue() { return true; } /** * Reads the long value from "somewhere". We could get this value from * physical hardware, files on disk, etc. For the purpose of this simple example, * 42 is returned. This implies every time the value of a BACI long property * that uses this class is accessed, 42 will be returned. * * Last but definitely not least, it is important to note that this method can be invoked * from both ROlong and RWlong properties. * @param errcode The error code (as defined in the ACS Error System) that occured while * reading this value or 0 if no error occured. It's up to the developer to * determine whether an error occured or not. * @param timestamp The time when the long value was read (presumably from hardware). * @return The value we are looking for. * @throw ACSErr::ACSbaseExImpl * @htmlonly
@endhtmlonly */ virtual CORBA::Long read(unsigned long long& timestamp) { //Must set the timestamp. This value is in 100s of nanoseconds that have passed //since some date in the 1500s. Most developers will just want to use the getTimeStamp //method, but you can find more information on the time defintion in the ACS Time //System. timestamp = getTimeStamp(); //Normally you'd want to access hardware, files, pipes, etc. here. We just return 42 return 42; } /** * Writes the long value to "someplace". This could be to physical hardware, files on * disk, etc. Every time the value of a BACI RWlong property using this class is set, * a message will be printed to standard out. * * Last but definitely not least, it is important to note this method can be only be invoked * from RWlong properties. * @param value The long value some ACS client (human or software) is trying to set for a * BACI RWlong property that uses this devIO subclass. * @param errcode The error code (as defined in the ACS Error System) that occured while * writing this value or 0 if no error occured. It's up to the developer to * determine whether an error occured or not. * @param timestamp The time when the long value was written (presumably to hardware). * @throw ACSErr::ACSbaseExImpl * @htmlonly
@endhtmlonly */ virtual void write(const CORBA::Long &value, unsigned long long& timestamp) { //Must set the timestamp. This value is in 100s of nanoseconds that have passed //since some date in the 1500s (see ACS Time System documentation for specific details). //Most developers will just want to use the getTimeStamp method. timestamp = getTimeStamp(); //Print a message to standard out std::cout << "LongDevIO::write(...) - the value is:" << value << std::endl; } }; #endif