LogFilterInterface.h

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// # LogFilterInterface.h: Abstract base class for filtering LogMessages
// # Copyright (C) 1996,2000,2003
// # 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: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef CASA_LOGFILTERINTERFACE_H
#define CASA_LOGFILTERINTERFACE_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Logging/LogMessage.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Abstract base class for filtering LogMessages.
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="wbrouw" date="1996/08/21" tests="" demos="dLogging.cc" tests="tLogging.cc">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="LogMessage">LogMessage</linkto>
// </prerequisite>
//
// <etymology>
// Log[Message] Filter.
// </etymology>
//
// <synopsis>
// The <src>LogFilter</src> class is used by the various log sink classes,
// typically accessed through <linkto class="LogSink">LogSink</linkto>, to
// decide whether a particular <linkto class="LogMessage">LogMessage</linkto>
// should be accepted or rejected.
//
// Simple filtering is based on the messages priority.
// In particular, you typically will choose to only pass messages greater
// than or equal to  <src>NORMAL</src> in priority, but you might choose
// <src>DEBUGGING</src> to see all messages, or <src>SEVERE</src> to only see
// messages that report serious problems.
// </synopsis>
//
// <example>
// Suppose we wanted to change the global sink so that it prints all messages,
// including debugging messages:
// <srcblock>
// LogFilter all(LogMessage::DEBUGGING);
// LogSink::globalSink().filter(all);
// </srcblock>
// </example>
//
// <motivation>
// </motivation>
//
// # <todo asof="1996/07/23">
// # </todo>
 
class LogFilterInterface {
 public:
  // Construct a filter with the LOWEST priority that you want passed.  Thus
  // <src>DEBUGGING</src> passes everything. Note that it is not possible to
  // block <src>SEVERE</src> level messages, although you can use a
  // <linkto class="NullLogSink">NullLogSink</linkto> which will have
  // this effect.
  LogFilterInterface() {}
 
  virtual ~LogFilterInterface();
 
  // Clone the object.
  virtual LogFilterInterface* clone() const = 0;
 
  // Return True if <src>message</src> passes this filter.
  virtual Bool pass(const LogMessage& message) const = 0;
 
 private:
  // Copy constructor and assignment cannot be used.
  // <group>
  LogFilterInterface(const LogFilterInterface& other);
  LogFilterInterface& operator=(const LogFilterInterface& other);
  // </group>
};
 
}  // namespace casacore
 
#endif