Re: f77_exception_encountered

[Paul Kienzle]

On Apr 1, 2004, at 6:24 PM, John W. Eaton wrote:

> Next, we check to see why we are inside this if block.  If it is
> because an f77 exception has occurred (i.e., xstopx has been called)
> then we print an error message and exit the if block (the
> F77_XFCN_ERROR macro just prints a message).  So I think the
> additional check of f77_exception_encountered after F77_XFCN is still
> needed.

Okay, obviously I didn't read it closely enough.  I was thrown by the
redundant error message in F77_XFCN_ERROR and in code such
as dbleQR.cc, both of which say something like, "error encountered
in subroutine XXX".  I guess you don't want to move error_state into
liboctave?

> We could change F77_XFCN_ERROR or F77_XFCN to throw a C++ exception
> here.  But if we do that, I think we will need to have a different way
> of printing tracebacks.  For example, we will need to catch exceptions
> everywhere we need to print traceback information.  At the same time,
> we should rething the use of error_state and error(), so that error()
> throws an exception instead of just printing a message and setting
> error_state.  I'm in favor of making changes like this because it will
> mean less code in user functions, and makes the C++ error() more like
> the Octave scripting error() function, but it will be a significant
> amount of work to make it all happen.

Exceptions might be nice, but I haven't worked enough with them to
know.  Certainly checking error_state and freeing resources
cleanly is a pain.  However, fixing something that ain't broke is
low on my priority list ;-)

Paul Kienzle
address@hidden