Re: SystemC exceptions and throw_it

John,

On 07/09/10 12:37, john.aynsley@doulos.com wrote:

> 1666-2005 has sc_report derived from std::exception, and for backward
> compatibility includes:
>
> typedef std::exception sc_exception;
>
> Should we mandate or recommend that user-defined exceptions thrown by
> throw_it are derived from std::exception?

Although it might be good practice in some cases, I would prefer not to
require derivation from std::exception. The thrown exceptions might be
used in similar scenarios (merely as tagged types) as sc_kill_exception
et.al., which do not need the overhead of std::exception.

  We could recommend it, though. Especially if the exception is
uncaught, the implementation can actually provide some information about
the thrown object, if it is derived from a known interface.

> Would someone care to provide me with a definition of class
> sc_unwind_exception?

I've played around with the detection of completely swallowed kills and
resets, and have used the definitions attached below.

  Note, that in this case, sc_unwind_exception is not derived from
std::exception and requires polymorphic usage in the catch clauses
(since it's abstract and does not have a public (copy) constructor).

  The constructors/destructor might not be needed in the standard, but
are used in the implementation to do the error checking.

Greetings from Oldenburg,
  Philipp

-- // from sc_except.h

class sc_unwind_exception
{
  virtual bool is_reset() const = 0;
protected:
  sc_unwind_exception();
  sc_unwind_exception( const sc_unwind_exception& );
  virtual ~sc_unwind_exception();
};

class sc_reset_exception
  : public sc_unwind_exception
{
public:
    virtual bool is_reset() const { return true; }
};

class sc_kill_exception
  : public sc_unwind_exception
{
public:
    virtual bool is_reset() const { return false; }
};

-- 
Philipp A. Hartmann
Hardware/Software Design Methodology Group
OFFIS
R&D Division Transportation | FuE-Bereich Verkehr
Escherweg 2 · 26121 Oldenburg · Germany
Phone/Fax: +49-441-9722-420/282 · PGP: 0x9161A5C0 · http://www.offis.de/
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