DRDE/AusRegCliever/include/IllegalSendError.h

83 lines
2.9 KiB
C
Raw Normal View History

2014-01-03 07:51:51 +00:00
#ifndef ILLEGAL_SEND_ERROR_H
#define ILLEGAL_SEND_ERROR_H
/**
\file
Class template definition file.
\copyright
Copyright (C) 2002, 2003 Oliver Schoenborn
This software is provided 'as-is', without
any express or implied warranty. In no event
will the authors be held liable for any
damages arising from the use of this
software.
You can redistribute it and/or modify it
under the terms found in the LICENSE file that
is included in the library distribution.
\endcopyright
*/
#include <string>
#include <sstream>
#include <typeinfo>
#include <stdexcept>
/**
\class EventSender<EvType>::IllegalSendError
An exception that gets thrown when EventSender<EvType>::send() is called
recursively at least once. This situation is more likely in complex
systems where events cause other events to be generated.
An example scenario is where you create an Type1Event and call
EventSender<Type1Event>::send(Type1Event). This call to send() in turn
calls the processEvent() method of a listener of Type1Event's.
If this listener's method creates another Type1Event and calls
EventSender<Type1Event>::send(Type1Event) on it, this will cause that
listener's processEvent() to be called once more, and the
process repeats. This is likely to trigger an infinite loop of
event generation. The only case where this would not happen is if
the listener keeps state information that changes between successive
calls to processEvent(), such that it does not generate an event
during one of those calls (the recursion ends), or if this listener
deregister's itself from listening.
Since an infinite recursion is likely to cause a program crash, and
since it is quite easy to make that kind of mistake, EventSender<EvType>
forbids calling send() while a send() (for that event type) is
in progress. It will throw a EventSender<EvType>::IllegalSendError if
such a situation occurs.
\author Oliver Schoenborn
\since Sept 2002
*/
template<typename EvType>
class EventSender<EvType>::IllegalSendError
: public std::logic_error
{
public:
/// Create the exception
IllegalSendError() : std::logic_error( msg() ) {}
private:
/// Prefix for each new line
static std::string nl() throw() { return "\n!!! "; }
/// The message to give to std::logic_error constructor.
static std::string msg()
{
std::ostringstream ss;
ss << nl() << "BUG alert (Recursive send forbidden): "
<< nl() << "Method send() of " << typeid(EventSender<EvType>).name()
<< nl() << "calls itself indirectly through listeners"
<< nl() << "(forbidden since could lead to infinite loop).";
return ss.str();
}
};
#endif // ILLEGAL_SEND_ERROR_H