Re: unwind_protect & try/catch combined corner case

[Søren Hauberg]

tor, 07 01 2010 kl. 09:46 +0100, skrev Jaroslav Hajek:
> But is the former correct? I believe it's the most reasonable behavior:
> the "try" section is entered, then unwind_protect. An interrupt occurs
> there, hence control is transferred to unwind_protect_cleanup.
> unwind_protect_cleanup executes some code which finally raises an
> error;

I'm with you so far...

>  however, this error is suppressed because we're in a "try"
> section.

I don't understand this. If you raise an error, shouldn't it be caught?
I think I would expect the following output from your program:

  cleanup inner
  caught error
  cleanup outer

I haven't tried your current code, but what is the result if the
following program?

  unwind_protect
    fdisp (stderr, "Press Ctrl-C");
    pause (3);
  unwind_protect_cleanup
    svd () # this raises an error
  end_unwind_protect

Will the user get the error message from 'svd' (which would be quite
helpful for debugging)? Will the user be able to catch this error?

Soren